Instruction prefetch based on thread dispatch commands

ABSTRACT

A graphics processing device is provided that includes a set of compute units to execute a workload, a cache coupled with the set of compute units, and circuitry coupled with the cache and the set of compute units. The circuitry is configured to, in response to a cache miss for the read from a first cache, broadcast an event within the graphics processor device to identify data associated with the cache miss, receive the event at a second compute unit in the set of compute units, and prefetch the data identified by the event into a second cache that is local to the second compute unit before an attempt to read the instruction or data by the second thread.

CROSS REFERENCE TO RELATED APPLICATIONS

The present patent application is a continuation application claimingpriority from U.S. application Ser. No. 17/509,726, filed Oct. 25, 2021,which is a continuation of U.S. application Ser. No. 16/243,663, filedJan. 9, 2019, issued as U.S. Pat. No. 11,157,283, the contents of whichare incorporated herein in their entirety by reference.

BACKGROUND

Computing systems may include a graphics processor to perform graphicsprocessing and parallel compute workloads such as linear interpolation,tessellation, rasterization, texture mapping, depth testing, etc.Traditionally, graphics processors used fixed function computationalunits to process graphics data. However, modern graphics processorsinclude programmable portions, enabling such processors to support awider variety of operations for processing vertex and fragment data, aswell as general-purpose parallel compute workloads. Such processorsgenerally include interfaces through which programmable workloads can bescheduled for execution on the processor. Programmable workloads can besubmitted in the form of shader programs, which can be configured toperform a variety of graphics, media, and compute processing workloads.For example, machine learning workloads can be performed by a graphicsprocessor via the use of compute shaders and/or special purpose logic.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments described herein are illustrated by way of example and notlimitation in the figures of the accompanying drawings in which likereferences indicate similar elements, and in which:

FIG. 1 is a block diagram of a processing system, according to anembodiment;

FIG. 2 is a block diagram of a processor according to an embodiment;

FIG. 3 is a block diagram of a graphics processor, according to anembodiment;

FIG. 4 is a block diagram of a graphics processing engine of a graphicsprocessor in accordance with some embodiments;

FIG. 5 is a block diagram of hardware logic of a graphics processorcore, according to some embodiments described herein;

FIGS. 6A-6B illustrate thread execution logic including an array ofprocessing elements employed in a graphics processor core according toembodiments described herein;

FIG. 7 is a block diagram illustrating a graphics processor instructionformats according to some embodiments;

FIG. 8 is a block diagram of a graphics processor according to anotherembodiment;

FIGS. 9A-9B illustrate a graphics processor command format and commandsequence, according to some embodiments;

FIG. 10 illustrates exemplary graphics software architecture for a dataprocessing system according to some embodiments;

FIG. 11A is a block diagram illustrating an IP core development system,according to an embodiment;

FIG. 11B illustrates a cross-section side view of an integrated circuitpackage assembly, according to some embodiments described herein;

FIG. 12 is a block diagram illustrating an exemplary system on a chipintegrated circuit, according to an embodiment;

FIGS. 13A-13B are block diagrams illustrating exemplary graphicsprocessors for use within an SoC, according to embodiments describedherein;

FIGS. 14A-14B illustrate additional exemplary graphics processor logicaccording to embodiments described herein;

FIG. 15 illustrates a data processing system according to embodimentsdescribed herein;

FIG. 16 illustrates a general-purpose compute architecture of a graphicsprocessor, as described herein;

FIG. 17 illustrates a graphics processing system, according toembodiments described herein;

FIG. 18 is a flow diagram of a method to prefetch kernel instructionsand/or data, according to an embodiment;

FIG. 19 illustrates a flow diagram of a method to prefetch kernelinstructions and/or data, according to an embodiment;

FIG. 20 illustrates a flow diagram of a method to prefetch kernelinstructions and/or data, according to an embodiment;

FIG. 21 illustrates a flow diagram of a method to bypass prefetch ofkernel instructions and/or data, according to an embodiment; and

FIG. 22 is a block diagram of a computing device including a graphicsprocessor, according to an embodiment.

DESCRIPTION OF EMBODIMENTS

Part of the scheduling process for parallel compute workloads includes athread dispatch phase in which multiple threads for a workload aredispatched to the various parallel compute units that will execute thethread. Thread dispatch within a graphics processor can be performed bya ‘walker’ component, which performs operations to walk the variouscompute units and distribute threads for execution. For short runningwalkers, the latency for instruction and data cold start can begin todominate the execution metrics. For example, walkers for machinelearning inference jobs running on a large server with small batch sizesmay have a short execution time, hence the time spent on loading thewalker and warming the cache will be important. Concepts provided by theembodiments described herein enable reduces instruction fetch time andreduce cold start latency for thread execution by prefetchinginstructions and/or parameters or constants for kernels to be executedin parallel with thread dispatch using data provided within a threaddispatch command. Other related techniques are also described.

For the purposes of explanation, numerous specific details are set forthto provide a thorough understanding of the various embodiments describedbelow. However, it will be apparent to a skilled practitioner in the artthat the embodiments may be practiced without some of these specificdetails. In other instances, well-known structures and devices are shownin block diagram form to avoid obscuring the underlying principles, andto provide a more thorough understanding of embodiments. Although someof the following embodiments are described with reference to a graphicsprocessor, the techniques and teachings described herein may be appliedto various types of circuits or semiconductor devices, including generalpurpose processing devices or graphic processing devices. Referenceherein to “one embodiment” or “an embodiment” indicate that a particularfeature, structure, or characteristic described in connection orassociation with the embodiment can be included in at least one of suchembodiments. However, the appearances of the phrase “in one embodiment”in various places in the specification do not necessarily all refer tothe same embodiment.

In the following description and claims, the terms “coupled” and“connected,” along with their derivatives, may be used. It should beunderstood that these terms are not intended as synonyms for each other.“Coupled” is used to indicate that two or more elements, which may ormay not be in direct physical or electrical contact with each other,co-operate or interact with each other. “Connected” is used to indicatethe establishment of communication between two or more elements that arecoupled with each other.

In the description that follows, FIGS. 1-14 provide an overview ofexemplary data processing system and graphics processor logic thatincorporates or relates to the various embodiments. FIGS. 15-22 providespecific details of the various embodiments. Some aspects of thefollowing embodiments are described with reference to a graphicsprocessor, while other aspects are described with respect to ageneral-purpose processor, such as a central processing unit (CPU).Similar techniques and teachings can be applied to other types ofcircuits or semiconductor devices, including but not limited to a manyintegrated core processor, a GPU cluster, or one or more instances of afield programmable gate array (FPGA). In general, the teachings areapplicable to any processor or machine that manipulates or processesimage (e.g., sample, pixel), vertex data, or geometry data.

System Overview

FIG. 1 is a block diagram of a processing system 100, according to anembodiment. In various embodiments the system 100 includes one or moreprocessors 102 and one or more graphics processors 108, and may be asingle processor desktop system, a multiprocessor workstation system, ora server system having a large number of processors 102 or processorcores 107. In one embodiment, the system 100 is a processing platformincorporated within a system-on-a-chip (SoC) integrated circuit for usein mobile, handheld, or embedded devices.

In one embodiment the system 100 can include or be incorporated within aserver-based gaming platform, a game console, including a game and mediaconsole, a mobile gaming console, a handheld game console, or an onlinegame console. In some embodiments the system 100 is a mobile phone,smart phone, tablet computing device or mobile Internet device. Theprocessing system 100 can also include, couple with, or be integratedwithin a wearable device, such as a smart watch wearable device, smarteyewear device, augmented reality device, or virtual reality device. Insome embodiments, the processing system 100 is a television or set topbox device having one or more processors 102 and a graphical interfacegenerated by one or more graphics processors 108.

In some embodiments, the one or more processors 102 each include one ormore processor cores 107 to process instructions which, when executed,perform operations for system and user software. In some embodiments,each of the one or more processor cores 107 is configured to process aspecific instruction set 109. In some embodiments, instruction set 109may facilitate Complex Instruction Set Computing (CISC), ReducedInstruction Set Computing (RISC), or computing via a Very LongInstruction Word (VLIW). Multiple processor cores 107 may each process adifferent instruction set 109, which may include instructions tofacilitate the emulation of other instruction sets. Processor core 107may also include other processing devices, such a Digital SignalProcessor (DSP).

In some embodiments, the processor 102 includes cache memory 104.Depending on the architecture, the processor 102 can have a singleinternal cache or multiple levels of internal cache. In someembodiments, the cache memory is shared among various components of theprocessor 102. In some embodiments, the processor 102 also uses anexternal cache (e.g., a Level-3 (L3) cache or Last Level Cache (LLC))(not shown), which may be shared among processor cores 107 using knowncache coherency techniques. A register file 106 is additionally includedin processor 102 which may include different types of registers forstoring different types of data (e.g., integer registers, floating-pointregisters, status registers, and an instruction pointer register). Someregisters may be general-purpose registers, while other registers may bespecific to the design of the processor 102.

In some embodiments, one or more processor(s) 102 are coupled with oneor more interface bus(es) 110 to transmit communication signals such asaddress, data, or control signals between processor 102 and othercomponents in the system 100. The interface bus 110, in one embodiment,can be a processor bus, such as a version of the Direct Media Interface(DMI) bus. However, processor busses are not limited to the DMI bus, andmay include one or more Peripheral Component Interconnect buses (e.g.,PCI, PCI Express), memory busses, or other types of interface busses. Inone embodiment the processor(s) 102 include an integrated memorycontroller 116 and a platform controller hub 130. The memory controller116 facilitates communication between a memory device and othercomponents of the system 100, while the platform controller hub (PCH)130 provides connections to I/O devices via a local I/O bus.

The memory device 120 can be a dynamic random-access memory (DRAM)device, a static random-access memory (SRAM) device, flash memorydevice, phase-change memory device, or some other memory device havingsuitable performance to serve as process memory. In one embodiment thememory device 120 can operate as system memory for the system 100, tostore data 122 and instructions 121 for use when the one or moreprocessors 102 executes an application or process. Memory controller 116also couples with an optional external graphics processor 112, which maycommunicate with the one or more graphics processors 108 in processors102 to perform graphics and media operations. In some embodiments adisplay device 111 can connect to the processor(s) 102. The displaydevice 111 can be one or more of an internal display device, as in amobile electronic device or a laptop device or an external displaydevice attached via a display interface (e.g., DisplayPort, etc.). Inone embodiment the display device 111 can be a head mounted display(HMD) such as a stereoscopic display device for use in virtual reality(VR) applications or augmented reality (AR) applications.

In some embodiments the platform controller hub 130 enables peripheralsto connect to memory device 120 and processor 102 via a high-speed I/Obus. The I/O peripherals include, but are not limited to, an audiocontroller 146, a network controller 134, a firmware interface 128, awireless transceiver 126, touch sensors 125, a data storage device 124(e.g., hard disk drive, flash memory, etc.). The data storage device 124can connect via a storage interface (e.g., SATA) or via a peripheralbus, such as a Peripheral Component Interconnect bus (e.g., PCI, PCIExpress). The touch sensors 125 can include touch screen sensors,pressure sensors, or fingerprint sensors. The wireless transceiver 126can be a Wi-Fi transceiver, a Bluetooth transceiver, or a mobile networktransceiver such as a 3G, 4G, or Long-Term Evolution (LTE) transceiver.The firmware interface 128 enables communication with system firmware,and can be, for example, a unified extensible firmware interface (UEFI).The network controller 134 can enable a network connection to a wirednetwork. In some embodiments, a high-performance network controller (notshown) couples with the interface bus 110. The audio controller 146, inone embodiment, is a multi-channel high definition audio controller. Inone embodiment the system 100 includes an optional legacy I/O controller140 for coupling legacy (e.g., Personal System 2 (PS/2)) devices to thesystem. The platform controller hub 130 can also connect to one or moreUniversal Serial Bus (USB) controllers 142 connect input devices, suchas keyboard and mouse 143 combinations, a camera 144, or other USB inputdevices.

It will be appreciated that the system 100 shown is exemplary and notlimiting, as other types of data processing systems that are differentlyconfigured may also be used. For example, an instance of the memorycontroller 116 and platform controller hub 130 may be integrated into adiscreet external graphics processor, such as the external graphicsprocessor 112. In one embodiment the platform controller hub 130 and/ormemory controller 160 may be external to the one or more processor(s)102. For example, the system 100 can include an external memorycontroller 116 and platform controller hub 130, which may be configuredas a memory controller hub and peripheral controller hub within a systemchipset that is in communication with the processor(s) 102.

FIG. 2 is a block diagram of an embodiment of a processor 200 having oneor more processor cores 202A-202N, an integrated memory controller 214,and an integrated graphics processor 208. Those elements of FIG. 2having the same reference numbers (or names) as the elements of anyother figure herein can operate or function in any manner similar tothat described elsewhere herein but are not limited to such. Processor200 can include additional cores up to and including additional core202N represented by the dashed lined boxes. Each of processor cores202A-202N includes one or more internal cache units 204A-204N. In someembodiments each processor core also has access to one or more sharedcached units 206.

The internal cache units 204A-204N and shared cache units 206 representa cache memory hierarchy within the processor 200. The cache memoryhierarchy may include at least one level of instruction and data cachewithin each processor core and one or more levels of shared mid-levelcache, such as a Level 2 (L2), Level 3 (L3), Level 4 (L4), or otherlevels of cache, where the highest level of cache before external memoryis classified as the LLC. In some embodiments, cache coherency logicmaintains coherency between the various cache units 206 and 204A-204N.

In some embodiments, processor 200 may also include a set of one or morebus controller units 216 and a system agent core 210. The one or morebus controller units 216 manage a set of peripheral buses, such as oneor more PCI or PCI express busses. System agent core 210 providesmanagement functionality for the various processor components. In someembodiments, system agent core 210 includes one or more integratedmemory controllers 214 to manage access to various external memorydevices (not shown).

In some embodiments, one or more of the processor cores 202A-202Ninclude support for simultaneous multi-threading. In such embodiment,the system agent core 210 includes components for coordinating andoperating cores 202A-202N during multi-threaded processing. System agentcore 210 may additionally include a power control unit (PCU), whichincludes logic and components to regulate the power state of processorcores 202A-202N and graphics processor 208.

In some embodiments, processor 200 additionally includes graphicsprocessor 208 to execute graphics processing operations. In someembodiments, the graphics processor 208 couples with the set of sharedcache units 206, and the system agent core 210, including the one ormore integrated memory controllers 214. In some embodiments, the systemagent core 210 also includes a display controller 211 to drive graphicsprocessor output to one or more coupled displays. In some embodiments,display controller 211 may also be a separate module coupled with thegraphics processor via at least one interconnect or may be integratedwithin the graphics processor 208.

In some embodiments, a ring-based interconnect 212 is used to couple theinternal components of the processor 200. However, an alternativeinterconnect unit may be used, such as a point-to-point interconnect, aswitched interconnect, or other techniques, including techniques wellknown in the art. In some embodiments, graphics processor 208 coupleswith the ring-based interconnect 212 via an I/O link 213.

The exemplary I/O link 213 represents at least one of multiple varietiesof I/O interconnects, including an on package I/O interconnect whichfacilitates communication between various processor components and ahigh-performance embedded memory module 218, such as an eDRAM module. Insome embodiments, each of the processor cores 202A-202N and graphicsprocessor 208 use embedded memory modules 218 as a shared Last LevelCache.

In some embodiments, processor cores 202A-202N are homogenous coresexecuting the same instruction set architecture. In another embodiment,processor cores 202A-202N are heterogeneous in terms of instruction setarchitecture (ISA), where one or more of processor cores 202A-202Nexecute a first instruction set, while at least one of the other coresexecutes a subset of the first instruction set or a differentinstruction set. In one embodiment processor cores 202A-202N areheterogeneous in terms of microarchitecture, where one or more coreshaving a relatively higher power consumption couple with one or morepower cores having a lower power consumption. Additionally, processor200 can be implemented on one or more chips or as an SoC integratedcircuit having the illustrated components, in addition to othercomponents.

FIG. 3 is a block diagram of a graphics processor 300, which may be adiscrete graphics processing unit, or may be a graphics processorintegrated with a plurality of processing cores. In some embodiments,the graphics processor communicates via a memory mapped I/O interface toregisters on the graphics processor and with commands placed into theprocessor memory. In some embodiments, graphics processor 300 includes amemory interface 314 to access memory. Memory interface 314 can be aninterface to local memory, one or more internal caches, one or moreshared external caches, and/or to system memory.

In some embodiments, graphics processor 300 also includes a displaycontroller 302 to drive display output data to a display device 320.Display controller 302 includes hardware for one or more overlay planesfor the display and composition of multiple layers of video or userinterface elements. The display device 320 can be an internal orexternal display device. In one embodiment the display device 320 is ahead mounted display device, such as a virtual reality (VR) displaydevice or an augmented reality (AR) display device. In some embodiments,graphics processor 300 includes a video codec engine 306 to encode,decode, or transcode media to, from, or between one or more mediaencoding formats, including, but not limited to Moving Picture ExpertsGroup (MPEG) formats such as MPEG-2, Advanced Video Coding (AVC) formatssuch as H.264/MPEG-4 AVC, as well as the Society of Motion Picture &Television Engineers (SMPTE) 421M/VC-1, and Joint Photographic ExpertsGroup (JPEG) formats such as JPEG, and Motion JPEG (MJPEG) formats.

In some embodiments, graphics processor 300 includes a block imagetransfer (BLIT) engine 304 to perform two-dimensional (2D) rasterizeroperations including, for example, bit-boundary block transfers.However, in one embodiment, 2D graphics operations are performed usingone or more components of graphics processing engine (GPE) 310. In someembodiments, GPE 310 is a compute engine for performing graphicsoperations, including three-dimensional (3D) graphics operations andmedia operations.

In some embodiments, GPE 310 includes a 3D pipeline 312 for performing3D operations, such as rendering three-dimensional images and scenesusing processing functions that act upon 3D primitive shapes (e.g.,rectangle, triangle, etc.). The 3D pipeline 312 includes programmableand fixed function elements that perform various tasks within theelement and/or spawn execution threads to a 3D/Media sub-system 315.While 3D pipeline 312 can be used to perform media operations, anembodiment of GPE 310 also includes a media pipeline 316 that isspecifically used to perform media operations, such as videopost-processing and image enhancement.

In some embodiments, media pipeline 316 includes fixed function orprogrammable logic units to perform one or more specialized mediaoperations, such as video decode acceleration, video de-interlacing, andvideo encode acceleration in place of, or on behalf of video codecengine 306. In some embodiments, media pipeline 316 additionallyincludes a thread spawning unit to spawn threads for execution on3D/Media sub-system 315. The spawned threads perform computations forthe media operations on one or more graphics execution units included in3D/Media sub-system 315.

In some embodiments, 3D/Media sub-system 315 includes logic forexecuting threads spawned by 3D pipeline 312 and media pipeline 316. Inone embodiment, the pipelines send thread execution requests to 3D/Mediasub-system 315, which includes thread dispatch logic for arbitrating anddispatching the various requests to available thread executionresources. The execution resources include an array of graphicsexecution units to process the 3D and media threads. In someembodiments, 3D/Media sub-system 315 includes one or more internalcaches for thread instructions and data. In some embodiments, thesub-system also includes shared memory, including registers andaddressable memory, to share data between threads and to store outputdata.

Graphics Processing Engine

FIG. 4 is a block diagram of a graphics processing engine 410 of agraphics processor in accordance with some embodiments. In oneembodiment, the graphics processing engine (GPE) 410 is a version of theGPE 310 shown in FIG. 3 . Elements of FIG. 4 having the same referencenumbers (or names) as the elements of any other figure herein canoperate or function in any manner similar to that described elsewhereherein, but are not limited to such. For example, the 3D pipeline 312and media pipeline 316 of FIG. 3 are illustrated. The media pipeline 316is optional in some embodiments of the GPE 410 and may not be explicitlyincluded within the GPE 410. For example, and in at least oneembodiment, a separate media and/or image processor is coupled to theGPE 410.

In some embodiments, GPE 410 couples with or includes a command streamer403, which provides a command stream to the 3D pipeline 312 and/or mediapipelines 316. In some embodiments, command streamer 403 is coupled withmemory, which can be system memory, or one or more of internal cachememory and shared cache memory. In some embodiments, command streamer403 receives commands from the memory and sends the commands to 3Dpipeline 312 and/or media pipeline 316. The commands are directivesfetched from a ring buffer, which stores commands for the 3D pipeline312 and media pipeline 316. In one embodiment, the ring buffer canadditionally include batch command buffers storing batches of multiplecommands. The commands for the 3D pipeline 312 can also includereferences to data stored in memory, such as but not limited to vertexand geometry data for the 3D pipeline 312 and/or image data and memoryobjects for the media pipeline 316. The 3D pipeline 312 and mediapipeline 316 process the commands and data by performing operations vialogic within the respective pipelines or by dispatching one or moreexecution threads to a graphics core array 414. In one embodiment thegraphics core array 414 include one or more blocks of graphics cores(e.g., graphics core(s) 415A, graphics core(s) 415B), each blockincluding one or more graphics cores. Each graphics core includes a setof graphics execution resources that includes general purpose andgraphics specific execution logic to perform graphics and computeoperations, as well as fixed function texture processing and/or machinelearning and artificial intelligence acceleration logic.

In various embodiments the 3D pipeline 312 includes fixed function andprogrammable logic to process one or more shader programs, such asvertex shaders, geometry shaders, pixel shaders, fragment shaders,compute shaders, or other shader programs, by processing theinstructions and dispatching execution threads to the graphics corearray 414. The graphics core array 414 provides a unified block ofexecution resources for use in processing these shader programs.Multi-purpose execution logic (e.g., execution units) within thegraphics core(s) 415A-414B of the graphics core array 414 includessupport for various 3D API shader languages and can execute multiplesimultaneous execution threads associated with multiple shaders.

In some embodiments the graphics core array 414 also includes executionlogic to perform media functions, such as video and/or image processing.In one embodiment, the execution units additionally includegeneral-purpose logic that is programmable to perform parallelgeneral-purpose computational operations, in addition to graphicsprocessing operations. The general-purpose logic can perform processingoperations in parallel or in conjunction with general purpose logicwithin the processor core(s) 107 of FIG. 1 or core 202A-202N as in FIG.2 .

Output data generated by threads executing on the graphics core array414 can output data to memory in a unified return buffer (URB) 418. TheURB 418 can store data for multiple threads. In some embodiments the URB418 may be used to send data between different threads executing on thegraphics core array 414. In some embodiments the URB 418 mayadditionally be used for synchronization between threads on the graphicscore array and fixed function logic within the shared function logic420.

In some embodiments, graphics core array 414 is scalable, such that thearray includes a variable number of graphics cores, each having avariable number of execution units based on the target power andperformance level of GPE 410. In one embodiment the execution resourcesare dynamically scalable, such that execution resources may be enabledor disabled as needed.

The graphics core array 414 couples with shared function logic 420 thatincludes multiple resources that are shared between the graphics coresin the graphics core array. The shared functions within the sharedfunction logic 420 are hardware logic units that provide specializedsupplemental functionality to the graphics core array 414. In variousembodiments, shared function logic 420 includes but is not limited tosampler 421, math 422, and inter-thread communication (ITC) 423 logic.Additionally, some embodiments implement one or more cache(s) 425 withinthe shared function logic 420.

A shared function is implemented where the demand for a givenspecialized function is insufficient for inclusion within the graphicscore array 414. Instead a single instantiation of that specializedfunction is implemented as a stand-alone entity in the shared functionlogic 420 and shared among the execution resources within the graphicscore array 414. The precise set of functions that are shared between thegraphics core array 414 and included within the graphics core array 414varies across embodiments. In some embodiments, specific sharedfunctions within the shared function logic 420 that are used extensivelyby the graphics core array 414 may be included within shared functionlogic 416 within the graphics core array 414. In various embodiments,the shared function logic 416 within the graphics core array 414 caninclude some or all logic within the shared function logic 420. In oneembodiment, all logic elements within the shared function logic 420 maybe duplicated within the shared function logic 416 of the graphics corearray 414. In one embodiment the shared function logic 420 is excludedin favor of the shared function logic 416 within the graphics core array414.

FIG. 5 is a block diagram of hardware logic of a graphics processor core500, according to some embodiments described herein. Elements of FIG. 5having the same reference numbers (or names) as the elements of anyother figure herein can operate or function in any manner similar tothat described elsewhere herein, but are not limited to such. Theillustrated graphics processor core 500, in some embodiments, isincluded within the graphics core array 414 of FIG. 4 . The graphicsprocessor core 500, sometimes referred to as a core slice, can be one ormultiple graphics cores within a modular graphics processor. Thegraphics processor core 500 is exemplary of one graphics core slice, anda graphics processor as described herein may include multiple graphicscore slices based on target power and performance envelopes. Eachgraphics core 500 can include a fixed function block 530 coupled withmultiple sub-cores 501A-501F, also referred to as sub-slices, thatinclude modular blocks of general purpose and fixed function logic.

In some embodiments the fixed function block 530 includes ageometry/fixed function pipeline 536 that can be shared by all sub-coresin the graphics processor 500, for example, in lower performance and/orlower power graphics processor implementations. In various embodiments,the geometry/fixed function pipeline 536 includes a 3D fixed functionpipeline (e.g., 3D pipeline 312 as in FIG. 3 and FIG. 4 ) a videofront-end unit, a thread spawner and thread dispatcher, and a unifiedreturn buffer manager, which manages unified return buffers, such as theunified return buffer 418 of FIG. 4 .

In one embodiment the fixed function block 530 also includes a graphicsSoC interface 537, a graphics microcontroller 538, and a media pipeline539. The graphics SoC interface 537 provides an interface between thegraphics core 500 and other processor cores within a system on a chipintegrated circuit. The graphics microcontroller 538 is a programmablesub-processor that is configurable to manage various functions of thegraphics processor 500, including thread dispatch, scheduling, andpre-emption. The media pipeline 539 (e.g., media pipeline 316 of FIG. 3and FIG. 4 ) includes logic to facilitate the decoding, encoding,pre-processing, and/or post-processing of multimedia data, includingimage and video data. The media pipeline 539 implement media operationsvia requests to compute or sampling logic within the sub-cores 501-501F.

In one embodiment the SoC interface 537 enables the graphics core 500 tocommunicate with general purpose application processor cores (e.g.,CPUs) and/or other components within an SoC, including memory hierarchyelements such as a shared last level cache memory, the system RAM,and/or embedded on-chip or on-package DRAM. The SoC interface 537 canalso enable communication with fixed function devices within the SoC,such as camera imaging pipelines, and enables the use of and/orimplements global memory atomics that may be shared between the graphicscore 500 and CPUs within the SoC. The SoC interface 537 can alsoimplement power management controls for the graphics core 500 and enablean interface between a clock domain of the graphic core 500 and otherclock domains within the SoC. In one embodiment the SoC interface 537enables receipt of command buffers from a command streamer and globalthread dispatcher that are configured to provide commands andinstructions to each of one or more graphics cores within a graphicsprocessor. The commands and instructions can be dispatched to the mediapipeline 539, when media operations are to be performed, or a geometryand fixed function pipeline (e.g., geometry and fixed function pipeline536, geometry and fixed function pipeline 514) when graphics processingoperations are to be performed.

The graphics microcontroller 538 can be configured to perform variousscheduling and management tasks for the graphics core 500. In oneembodiment the graphics microcontroller 538 can perform graphics and/orcompute workload scheduling on the various graphics parallel engineswithin execution unit (EU) arrays 502A-502F, 504A-504F within thesub-cores 501A-501F. In this scheduling model, host software executingon a CPU core of an SoC including the graphics core 500 can submitworkloads one of multiple graphic processor doorbells, which invokes ascheduling operation on the appropriate graphics engine. Schedulingoperations include determining which workload to run next, submitting aworkload to a command streamer, pre-empting existing workloads runningon an engine, monitoring progress of a workload, and notifying hostsoftware when a workload is complete. In one embodiment the graphicsmicrocontroller 538 can also facilitate low-power or idle states for thegraphics core 500, providing the graphics core 500 with the ability tosave and restore registers within the graphics core 500 across low-powerstate transitions independently from the operating system and/orgraphics driver software on the system.

The graphics core 500 may have greater than or fewer than theillustrated sub-cores 501A-501F, up to N modular sub-cores. For each setof N sub-cores, the graphics core 500 can also include shared functionlogic 510, shared and/or cache memory 512, a geometry/fixed functionpipeline 514, as well as additional fixed function logic 516 toaccelerate various graphics and compute processing operations. Theshared function logic 510 can include logic units associated with theshared function logic 420 of FIG. 4 (e.g., sampler, math, and/orinter-thread communication logic) that can be shared by each N sub-coreswithin the graphics core 500. The shared and/or cache memory 512 can bea last-level cache for the set of N sub-cores 501A-501F within thegraphics core 500, and can also serve as shared memory that isaccessible by multiple sub-cores. The geometry/fixed function pipeline514 can be included instead of the geometry/fixed function pipeline 536within the fixed function block 530 and can include the same or similarlogic units.

In one embodiment the graphics core 500 includes additional fixedfunction logic 516 that can include various fixed function accelerationlogic for use by the graphics core 500. In one embodiment the additionalfixed function logic 516 includes an additional geometry pipeline foruse in position only shading. In position-only shading, two geometrypipelines exist, the full geometry pipeline within the geometry/fixedfunction pipeline 516, 536, and a cull pipeline, which is an additionalgeometry pipeline which may be included within the additional fixedfunction logic 516. In one embodiment the cull pipeline is a trimmeddown version of the full geometry pipeline. The full pipeline and thecull pipeline can execute different instances of the same application,each instance having a separate context. Position only shading can hidelong cull runs of discarded triangles, enabling shading to be completedearlier in some instances. For example, and in one embodiment the cullpipeline logic within the additional fixed function logic 516 canexecute position shaders in parallel with the main application andgenerally generates critical results faster than the full pipeline, asthe cull pipeline fetches and shades only the position attribute of thevertices, without performing rasterization and rendering of the pixelsto the frame buffer. The cull pipeline can use the generated criticalresults to compute visibility information for all the triangles withoutregard to whether those triangles are culled. The full pipeline (whichin this instance may be referred to as a replay pipeline) can consumethe visibility information to skip the culled triangles to shade onlythe visible triangles that are finally passed to the rasterizationphase.

In one embodiment the additional fixed function logic 516 can alsoinclude machine-learning acceleration logic, such as fixed functionmatrix multiplication logic, for implementations including optimizationsfor machine learning training or inferencing.

Within each graphics sub-core 501A-501F includes a set of executionresources that may be used to perform graphics, media, and computeoperations in response to requests by graphics pipeline, media pipeline,or shader programs. The graphics sub-cores 501A-501F include multiple EUarrays 502A-502F, 504A-504F, thread dispatch and inter-threadcommunication (TD/IC) logic 503A-503F, a 3D (e.g., texture) sampler505A-505F, a media sampler 506A-506F, a shader processor 507A-507F, andshared local memory (SLM) 508A-508F. The EU arrays 502A-502F, 504A-504Feach include multiple execution units, which are general-purposegraphics processing units capable of performing floating-point andinteger/fixed-point logic operations in service of a graphics, media, orcompute operation, including graphics, media, or compute shaderprograms. The TD/IC logic 503A-503F performs local thread dispatch andthread control operations for the execution units within a sub-core andfacilitate communication between threads executing on the executionunits of the sub-core. The 3D sampler 505A-505F can read texture orother 3D graphics related data into memory. The 3D sampler can readtexture data differently based on a configured sample state and thetexture format associated with a given texture. The media sampler506A-506F can perform similar read operations based on the type andformat associated with media data. In one embodiment, each graphicssub-core 501A-501F can alternately include a unified 3D and mediasampler. Threads executing on the execution units within each of thesub-cores 501A-501F can make use of shared local memory 508A-508F withineach sub-core, to enable threads executing within a thread group toexecute using a common pool of on-chip memory.

Execution Units

FIGS. 6A-6B illustrate thread execution logic 600 including an array ofprocessing elements employed in a graphics processor core according toembodiments described herein. Elements of FIGS. 6A-6B having the samereference numbers (or names) as the elements of any other figure hereincan operate or function in any manner similar to that describedelsewhere herein, but are not limited to such. FIG. 6A illustrates anoverview of thread execution logic 600, which can include a variant ofthe hardware logic illustrated with each sub-core 501A-501F of FIG. 5 .FIG. 6B illustrates exemplary internal details of an execution unit.

As illustrated in FIG. 6A, in some embodiments thread execution logic600 includes a shader processor 602, a thread dispatcher 604,instruction cache 606, a scalable execution unit array including aplurality of execution units 608A-608N, a sampler 610, a data cache 612,and a data port 614. In one embodiment the scalable execution unit arraycan dynamically scale by enabling or disabling one or more executionunits (e.g., any of execution unit 608A, 608B, 608C, 608D, through608N-1 and 608N) based on the computational requirements of a workload.In one embodiment the included components are interconnected via aninterconnect fabric that links to each of the components. In someembodiments, thread execution logic 600 includes one or more connectionsto memory, such as system memory or cache memory, through one or more ofinstruction cache 606, data port 614, sampler 610, and execution units608A-608N. In some embodiments, each execution unit (e.g. 608A) is astand-alone programmable general-purpose computational unit that iscapable of executing multiple simultaneous hardware threads whileprocessing multiple data elements in parallel for each thread. Invarious embodiments, the array of execution units 608A-608N is scalableto include any number individual execution units.

In some embodiments, the execution units 608A-608N are primarily used toexecute shader programs. A shader processor 602 can process the variousshader programs and dispatch execution threads associated with theshader programs via a thread dispatcher 604. In one embodiment thethread dispatcher includes logic to arbitrate thread initiation requestsfrom the graphics and media pipelines and instantiate the requestedthreads on one or more execution unit in the execution units 608A-608N.For example, a geometry pipeline can dispatch vertex, tessellation, orgeometry shaders to the thread execution logic for processing. In someembodiments, thread dispatcher 604 can also process runtime threadspawning requests from the executing shader programs.

In some embodiments, the execution units 608A-608N support aninstruction set that includes native support for many standard 3Dgraphics shader instructions, such that shader programs from graphicslibraries (e.g., Direct 3D and OpenGL) are executed with a minimaltranslation. The execution units support vertex and geometry processing(e.g., vertex programs, geometry programs, vertex shaders), pixelprocessing (e.g., pixel shaders, fragment shaders) and general-purposeprocessing (e.g., compute and media shaders). Each of the executionunits 608A-608N is capable of multi-issue single instruction multipledata (SIMD) execution and multi-threaded operation enables an efficientexecution environment in the face of higher latency memory accesses.Each hardware thread within each execution unit has a dedicatedhigh-bandwidth register file and associated independent thread-state.Execution is multi-issue per clock to pipelines capable of integer,single and double precision floating-point operations, SIMD branchcapability, logical operations, transcendental operations, and othermiscellaneous operations. While waiting for data from memory or one ofthe shared functions, dependency logic within the execution units608A-608N causes a waiting thread to sleep until the requested data hasbeen returned. While the waiting thread is sleeping, hardware resourcesmay be devoted to processing other threads. For example, during a delayassociated with a vertex shader operation, an execution unit can performoperations for a pixel shader, fragment shader, or another type ofshader program, including a different vertex shader.

Each execution unit in execution units 608A-608N operates on arrays ofdata elements. The number of data elements is the “execution size,” orthe number of channels for the instruction. An execution channel is alogical unit of execution for data element access, masking, and flowcontrol within instructions. The number of channels may be independentof the number of physical Arithmetic Logic Units (ALUs) orFloating-point Units (FPUs) for a particular graphics processor. In someembodiments, execution units 608A-608N support integer andfloating-point data types.

The execution unit instruction set includes SIMD instructions. Thevarious data elements can be stored as a packed data type in a registerand the execution unit will process the various elements based on thedata size of the elements. For example, when operating on a 256-bit widevector, the 256 bits of the vector are stored in a register and theexecution unit operates on the vector as four separate 64-bit packeddata elements (Quad-Word (QW) size data elements), eight separate 32-bitpacked data elements (Double Word (DW) size data elements), sixteenseparate 16-bit packed data elements (Word (W) size data elements), orthirty-two separate 8-bit data elements (byte (B) size data elements).However, different vector widths and register sizes are possible.

In one embodiment one or more execution units can be combined into afused execution unit 609A-609N having thread control logic (607A-607N)that is common to the fused EUs. Multiple EUs can be fused into an EUgroup. Each EU in the fused EU group can be configured to execute aseparate SIMD hardware thread. The number of EUs in a fused EU group canvary according to embodiments. Additionally, various SIMD widths can beperformed per-EU, including but not limited to SIMD8, SIMD16, andSIMD32. Each fused graphics execution unit 609A-609N includes at leasttwo execution units. For example, fused execution unit 609A includes afirst EU 608A, second EU 608B, and thread control logic 607A that iscommon to the first EU 608A and the second EU 608B. The thread controllogic 607A controls threads executed on the fused graphics executionunit 609A, allowing each EU within the fused execution units 609A-609Nto execute using a common instruction pointer register.

One or more internal instruction caches (e.g., 606) are included in thethread execution logic 600 to cache thread instructions for theexecution units. In some embodiments, one or more data caches (e.g.,612) are included to cache thread data during thread execution. In someembodiments, a sampler 610 is included to provide texture sampling for3D operations and media sampling for media operations. In someembodiments, sampler 610 includes specialized texture or media samplingfunctionality to process texture or media data during the samplingprocess before providing the sampled data to an execution unit.

During execution, the graphics and media pipelines send threadinitiation requests to thread execution logic 600 via thread spawningand dispatch logic. Once a group of geometric objects has been processedand rasterized into pixel data, pixel processor logic (e.g., pixelshader logic, fragment shader logic, etc.) within the shader processor602 is invoked to further compute output information and cause resultsto be written to output surfaces (e.g., color buffers, depth buffers,stencil buffers, etc.). In some embodiments, a pixel shader or fragmentshader calculates the values of the various vertex attributes that areto be interpolated across the rasterized object. In some embodiments,pixel processor logic within the shader processor 602 then executes anapplication programming interface (API)-supplied pixel or fragmentshader program. To execute the shader program, the shader processor 602dispatches threads to an execution unit (e.g., 608A) via threaddispatcher 604. In some embodiments, shader processor 602 uses texturesampling logic in the sampler 610 to access texture data in texture mapsstored in memory. Arithmetic operations on the texture data and theinput geometry data compute pixel color data for each geometricfragment, or discards one or more pixels from further processing.

In some embodiments, the data port 614 provides a memory accessmechanism for the thread execution logic 600 to output processed data tomemory for further processing on a graphics processor output pipeline.In some embodiments, the data port 614 includes or couples to one ormore cache memories (e.g., data cache 612) to cache data for memoryaccess via the data port.

As illustrated in FIG. 6B, a graphics execution unit 608 can include aninstruction fetch unit 637, a general register file array (GRF) 624, anarchitectural register file array (ARF) 626, a thread arbiter 622, asend unit 630, a branch unit 632, a set of SIMD floating-point units(FPUs) 634, and in one embodiment a set of dedicated integer SIMD ALUs635. The GRF 624 and ARF 626 includes the set of general register filesand architecture register files associated with each simultaneoushardware thread that may be active in the graphics execution unit 608.In one embodiment, per thread architectural state is maintained in theARF 626, while data used during thread execution is stored in the GRF624. The execution state of each thread, including the instructionpointers for each thread, can be held in thread-specific registers inthe ARF 626.

In one embodiment the graphics execution unit 608 has an architecturethat is a combination of Simultaneous Multi-Threading (SMT) andfine-grained Interleaved Multi-Threading (IMT). The architecture has amodular configuration that can be fine-tuned at design time based on atarget number of simultaneous threads and number of registers perexecution unit, where execution unit resources are divided across logicused to execute multiple simultaneous threads.

In one embodiment, the graphics execution unit 608 can co-issue multipleinstructions, which may each be different instructions. The threadarbiter 622 of the graphics execution unit 608 can dispatch theinstructions to one of the send unit 630, branch unit 642, or SIMDFPU(s) 634 for execution. Each execution thread can access 128general-purpose registers within the GRF 624, where each register canstore 32 bytes, accessible as a SIMD 8-element vector of 32-bit dataelements. In one embodiment, each execution unit thread has access to 4Kbytes within the GRF 624, although embodiments are not so limited, andgreater or fewer register resources may be provided in otherembodiments. In one embodiment up to seven threads can executesimultaneously, although the number of threads per execution unit canalso vary according to embodiments. In an embodiment in which seventhreads may access 4 Kbytes, the GRF 624 can store a total of 28 Kbytes.Flexible addressing modes can permit registers to be addressed togetherto build effectively wider registers or to represent strided rectangularblock data structures.

In one embodiment, memory operations, sampler operations, and otherlonger-latency system communications are dispatched via “send”instructions that are executed by the message passing send unit 630. Inone embodiment, branch instructions are dispatched to a dedicated branchunit 632 to facilitate SIMD divergence and eventual convergence.

In one embodiment the graphics execution unit 608 includes one or moreSIMD floating-point units (FPU(s)) 634 to perform floating-pointoperations. In one embodiment, the FPU(s) 634 also support integercomputation. In one embodiment the FPU(s) 634 can SIMD execute up to Mnumber of 32-bit floating-point (or integer) operations, or SIMD executeup to 2M 16-bit integer or 16-bit floating-point operations. In oneembodiment, at least one of the FPU(s) provides extended math capabilityto support high-throughput transcendental math functions and doubleprecision 64-bit floating-point. In some embodiments, a set of 8-bitinteger SIMD ALUs 635 are also present, and may be specificallyoptimized to perform operations associated with machine learningcomputations.

In one embodiment, arrays of multiple instances of the graphicsexecution unit 608 can be instantiated in a graphics sub-core grouping(e.g., a sub-slice). For scalability, product architects can choose theexact number of execution units per sub-core grouping. In one embodimentthe graphics execution unit 608 can execute instructions across aplurality of execution channels. In a further embodiment, each threadexecuted on the graphics execution unit 608 is executed on a differentchannel.

FIG. 7 is a block diagram illustrating a graphics processor instructionformats 700 according to some embodiments. In one or more embodiment,the graphics processor execution units support an instruction set havinginstructions in multiple formats. The solid lined boxes illustrate thecomponents that are generally included in an execution unit instruction,while the dashed lines include components that are optional or that areonly included in a sub-set of the instructions. In some embodiments, theinstruction formats 700 described and illustrated aremacro-instructions, in that they are instructions supplied to theexecution unit, as opposed to micro-operations resulting frominstruction decode once the instruction is processed.

In some embodiments, the graphics processor execution units nativelysupport instructions in a 128-bit instruction format 710. A 64-bitcompacted instruction format 730 is available for some instructionsbased on the selected instruction, instruction options, and number ofoperands. The native 128-bit instruction format 710 provides access toall instruction options, while some options and operations arerestricted in the 64-bit format 730. The native instructions availablein the 64-bit format 730 vary by embodiment. In some embodiments, theinstruction is compacted in part using a set of index values in an indexfield 713. The execution unit hardware references a set of compactiontables based on the index values and uses the compaction table outputsto reconstruct a native instruction in the 128-bit instruction format710.

For each format, instruction opcode 712 defines the operation that theexecution unit is to perform. The execution units execute eachinstruction in parallel across the multiple data elements of eachoperand. For example, in response to an add instruction the executionunit performs a simultaneous add operation across each color channelrepresenting a texture element or picture element. By default, theexecution unit performs each instruction across all data channels of theoperands. In some embodiments, instruction control field 714 enablescontrol over certain execution options, such as channels selection(e.g., predication) and data channel order (e.g., swizzle). Forinstructions in the 128-bit instruction format 710 an exec-size field716 limits the number of data channels that will be executed inparallel. In some embodiments, exec-size field 716 is not available foruse in the 64-bit compact instruction format 730.

Some execution unit instructions have up to three operands including twosource operands, src0 720, src1 722, and one destination 718. In someembodiments, the execution units support dual destination instructions,where one of the destinations is implied. Data manipulation instructionscan have a third source operand (e.g., SRC2 724), where the instructionopcode 712 determines the number of source operands. An instruction'slast source operand can be an immediate (e.g., hard-coded) value passedwith the instruction.

In some embodiments, the 128-bit instruction format 710 includes anaccess/address mode field 726 specifying, for example, whether directregister addressing mode or indirect register addressing mode is used.When direct register addressing mode is used, the register address ofone or more operands is directly provided by bits in the instruction.

In some embodiments, the 128-bit instruction format 710 includes anaccess/address mode field 726, which specifies an address mode and/or anaccess mode for the instruction. In one embodiment the access mode isused to define a data access alignment for the instruction. Someembodiments support access modes including a 16-byte aligned access modeand a 1-byte aligned access mode, where the byte alignment of the accessmode determines the access alignment of the instruction operands. Forexample, when in a first mode, the instruction may use byte-alignedaddressing for source and destination operands and when in a secondmode, the instruction may use 16-byte-aligned addressing for all sourceand destination operands.

In one embodiment, the address mode portion of the access/address modefield 726 determines whether the instruction is to use direct orindirect addressing. When direct register addressing mode is used bitsin the instruction directly provide the register address of one or moreoperands. When indirect register addressing mode is used, the registeraddress of one or more operands may be computed based on an addressregister value and an address immediate field in the instruction.

In some embodiments instructions are grouped based on opcode 712bit-fields to simplify Opcode decode 740. For an 8-bit opcode, bits 4,5, and 6 allow the execution unit to determine the type of opcode. Theprecise opcode grouping shown is merely an example. In some embodiments,a move and logic opcode group 742 includes data movement and logicinstructions (e.g., move (mov), compare (cmp)). In some embodiments,move and logic group 742 shares the five most significant bits (MSB),where move (mov) instructions are in the form of 0000xxxxb and logicinstructions are in the form of 0001xxxxb. A flow control instructiongroup 744 (e.g., call, jump (jmp)) includes instructions in the form of00xxxxb (e.g., 0x20). A miscellaneous instruction group 746 includes amix of instructions, including synchronization instructions (e.g., wait,send) in the form of 0011xxxxb (e.g., 0x30). A parallel math instructiongroup 748 includes component-wise arithmetic instructions (e.g., add,multiply (mul)) in the form of 0100xxxxb (e.g., 0x40). The parallel mathgroup 748 performs the arithmetic operations in parallel across datachannels. The vector math group 750 includes arithmetic instructions(e.g., dp4) in the form of 0101xxxxb (e.g., 0x50). The vector math groupperforms arithmetic such as dot product calculations on vector operands.

Graphics Pipeline

FIG. 8 is a block diagram of another embodiment of a graphics processor800. Elements of FIG. 8 having the same reference numbers (or names) asthe elements of any other figure herein can operate or function in anymanner similar to that described elsewhere herein, but are not limitedto such.

In some embodiments, graphics processor 800 includes a geometry pipeline820, a media pipeline 830, a display engine 840, thread execution logic850, and a render output pipeline 870. In some embodiments, graphicsprocessor 800 is a graphics processor within a multi-core processingsystem that includes one or more general purpose processing cores. Thegraphics processor is controlled by register writes to one or morecontrol registers (not shown) or via commands issued to graphicsprocessor 800 via a ring interconnect 802. In some embodiments, ringinterconnect 802 couples graphics processor 800 to other processingcomponents, such as other graphics processors or general-purposeprocessors. Commands from ring interconnect 802 are interpreted by acommand streamer 803, which supplies instructions to individualcomponents of the geometry pipeline 820 or the media pipeline 830.

In some embodiments, command streamer 803 directs the operation of avertex fetcher 805 that reads vertex data from memory and executesvertex-processing commands provided by command streamer 803. In someembodiments, vertex fetcher 805 provides vertex data to a vertex shader807, which performs coordinate space transformation and lightingoperations to each vertex. In some embodiments, vertex fetcher 805 andvertex shader 807 execute vertex-processing instructions by dispatchingexecution threads to execution units 852A-852B via a thread dispatcher831.

In some embodiments, execution units 852A-852B are an array of vectorprocessors having an instruction set for performing graphics and mediaoperations. In some embodiments, execution units 852A-852B have anattached L1 cache 851 that is specific for each array or shared betweenthe arrays. The cache can be configured as a data cache, an instructioncache, or a single cache that is partitioned to contain data andinstructions in different partitions.

In some embodiments, geometry pipeline 820 includes tessellationcomponents to perform hardware-accelerated tessellation of 3D objects.In some embodiments, a programmable hull shader 811 configures thetessellation operations. A programmable domain shader 817 providesback-end evaluation of tessellation output. A tessellator 813 operatesat the direction of hull shader 811 and contains special purpose logicto generate a set of detailed geometric objects based on a coarsegeometric model that is provided as input to geometry pipeline 820. Insome embodiments, if tessellation is not used, tessellation components(e.g., hull shader 811, tessellator 813, and domain shader 817) can bebypassed.

In some embodiments, complete geometric objects can be processed by ageometry shader 819 via one or more threads dispatched to executionunits 852A-852B, or can proceed directly to the clipper 829. In someembodiments, the geometry shader operates on entire geometric objects,rather than vertices or patches of vertices as in previous stages of thegraphics pipeline. If the tessellation is disabled, the geometry shader819 receives input from the vertex shader 807. In some embodiments,geometry shader 819 is programmable by a geometry shader program toperform geometry tessellation if the tessellation units are disabled.

Before rasterization, a clipper 829 can process vertex data. The clipper829 may be a fixed function clipper or a programmable clipper havingclipping and geometry shader functions. In some embodiments, arasterizer and depth test component 873 in the render output pipeline870 dispatches pixel shaders to convert the geometric objects into perpixel representations. In some embodiments, pixel shader logic isincluded in thread execution logic 850. In some embodiments, anapplication can bypass the rasterizer and depth test component 873 andaccess un-rasterized vertex data via a stream out unit 823.

The graphics processor 800 has an interconnect bus, interconnect fabric,or some other interconnect mechanism that allows data and messagepassing amongst the major components of the processor. In someembodiments, execution units 852A-852B and associated logic units (e.g.,L1 cache 851, sampler 854, texture cache 858, etc.) interconnect via adata port 856 to perform memory access and communicate with renderoutput pipeline components of the processor. In some embodiments,sampler 854, caches 851, 858 and execution units 852A-852B each haveseparate memory access paths. In one embodiment the texture cache 858can also be configured as a sampler cache.

In some embodiments, render output pipeline 870 contains a rasterizerand depth test component 873 that converts vertex-based objects into anassociated pixel-based representation. In some embodiments, therasterizer logic includes a windower/masker unit to perform fixedfunction triangle and line rasterization. An associated render cache 878and depth cache 879 are also available in some embodiments. A pixeloperations component 877 performs pixel-based operations on the data,though in some instances, pixel operations associated with 2D operations(e.g. bit block image transfers with blending) are performed by the 2Dengine 841, or substituted at display time by the display controller 843using overlay display planes. In some embodiments, a shared L3 cache 875is available to all graphics components, allowing the sharing of datawithout the use of main system memory.

In some embodiments, graphics processor media pipeline 830 includes amedia engine 837 and a video front-end 834. In some embodiments, videofront-end 834 receives pipeline commands from the command streamer 803.In some embodiments, media pipeline 830 includes a separate commandstreamer. In some embodiments, video front-end 834 processes mediacommands before sending the command to the media engine 837. In someembodiments, media engine 837 includes thread spawning functionality tospawn threads for dispatch to thread execution logic 850 via threaddispatcher 831.

In some embodiments, graphics processor 800 includes a display engine840. In some embodiments, display engine 840 is external to processor800 and couples with the graphics processor via the ring interconnect802, or some other interconnect bus or fabric. In some embodiments,display engine 840 includes a 2D engine 841 and a display controller843. In some embodiments, display engine 840 contains special purposelogic capable of operating independently of the 3D pipeline. In someembodiments, display controller 843 couples with a display device (notshown), which may be a system integrated display device, as in a laptopcomputer, or an external display device attached via a display deviceconnector.

In some embodiments, the geometry pipeline 820 and media pipeline 830are configurable to perform operations based on multiple graphics andmedia programming interfaces and are not specific to any one applicationprogramming interface (API). In some embodiments, driver software forthe graphics processor translates API calls that are specific to aparticular graphics or media library into commands that can be processedby the graphics processor. In some embodiments, support is provided forthe Open Graphics Library (OpenGL), Open Computing Language (OpenCL),and/or Vulkan graphics and compute API, all from the Khronos Group. Insome embodiments, support may also be provided for the Direct3D libraryfrom the Microsoft Corporation. In some embodiments, a combination ofthese libraries may be supported. Support may also be provided for theOpen Source Computer Vision Library (OpenCV). A future API with acompatible 3D pipeline would also be supported if a mapping can be madefrom the pipeline of the future API to the pipeline of the graphicsprocessor.

Graphics Pipeline Programming

FIG. 9A is a block diagram illustrating a graphics processor commandformat 900 according to some embodiments. FIG. 9B is a block diagramillustrating a graphics processor command sequence 910 according to anembodiment. The solid lined boxes in FIG. 9A illustrate the componentsthat are generally included in a graphics command while the dashed linesinclude components that are optional or that are only included in asub-set of the graphics commands. The exemplary graphics processorcommand format 900 of FIG. 9A includes data fields to identify a client902, a command operation code (opcode) 904, and data 906 for thecommand. A sub-opcode 905 and a command size 908 are also included insome commands.

In some embodiments, client 902 specifies the client unit of thegraphics device that processes the command data. In some embodiments, agraphics processor command parser examines the client field of eachcommand to condition the further processing of the command and route thecommand data to the appropriate client unit. In some embodiments, thegraphics processor client units include a memory interface unit, arender unit, a 2D unit, a 3D unit, and a media unit. Each client unithas a corresponding processing pipeline that processes the commands.Once the command is received by the client unit, the client unit readsthe opcode 904 and, if present, sub-opcode 905 to determine theoperation to perform. The client unit performs the command usinginformation in data field 906. For some commands an explicit commandsize 908 is expected to specify the size of the command. In someembodiments, the command parser automatically determines the size of atleast some of the commands based on the command opcode. In someembodiments commands are aligned via multiples of a double word.

The flow diagram in FIG. 9B illustrates an exemplary graphics processorcommand sequence 910. In some embodiments, software or firmware of adata processing system that features an embodiment of a graphicsprocessor uses a version of the command sequence shown to set up,execute, and terminate a set of graphics operations. A sample commandsequence is shown and described for purposes of example only asembodiments are not limited to these specific commands or to thiscommand sequence. Moreover, the commands may be issued as batch ofcommands in a command sequence, such that the graphics processor willprocess the sequence of commands in at least partially concurrence.

In some embodiments, the graphics processor command sequence 910 maybegin with a pipeline flush command 912 to cause any active graphicspipeline to complete the currently pending commands for the pipeline. Insome embodiments, the 3D pipeline 922 and the media pipeline 924 do notoperate concurrently. The pipeline flush is performed to cause theactive graphics pipeline to complete any pending commands. In responseto a pipeline flush, the command parser for the graphics processor willpause command processing until the active drawing engines completepending operations and the relevant read caches are invalidated.Optionally, any data in the render cache that is marked ‘dirty’ can beflushed to memory. In some embodiments, pipeline flush command 912 canbe used for pipeline synchronization or before placing the graphicsprocessor into a low power state.

In some embodiments, a pipeline select command 913 is used when acommand sequence requires the graphics processor to explicitly switchbetween pipelines. In some embodiments, a pipeline select command 913 isrequired only once within an execution context before issuing pipelinecommands unless the context is to issue commands for both pipelines. Insome embodiments, a pipeline flush command 912 is required immediatelybefore a pipeline switch via the pipeline select command 913.

In some embodiments, a pipeline control command 914 configures agraphics pipeline for operation and is used to program the 3D pipeline922 and the media pipeline 924. In some embodiments, pipeline controlcommand 914 configures the pipeline state for the active pipeline. Inone embodiment, the pipeline control command 914 is used for pipelinesynchronization and to clear data from one or more cache memories withinthe active pipeline before processing a batch of commands.

In some embodiments, return buffer state commands 916 are used toconfigure a set of return buffers for the respective pipelines to writedata. Some pipeline operations require the allocation, selection, orconfiguration of one or more return buffers into which the operationswrite intermediate data during processing. In some embodiments, thegraphics processor also uses one or more return buffers to store outputdata and to perform cross thread communication. In some embodiments, thereturn buffer state 916 includes selecting the size and number of returnbuffers to use for a set of pipeline operations.

The remaining commands in the command sequence differ based on theactive pipeline for operations. Based on a pipeline determination 920,the command sequence is tailored to the 3D pipeline 922 beginning withthe 3D pipeline state 930 or the media pipeline 924 beginning at themedia pipeline state 940.

The commands to configure the 3D pipeline state 930 include 3D statesetting commands for vertex buffer state, vertex element state, constantcolor state, depth buffer state, and other state variables that are tobe configured before 3D primitive commands are processed. The values ofthese commands are determined at least in part based on the particular3D API in use. In some embodiments, 3D pipeline state 930 commands arealso able to selectively disable or bypass certain pipeline elements ifthose elements will not be used.

In some embodiments, 3D primitive 932 command is used to submit 3Dprimitives to be processed by the 3D pipeline. Commands and associatedparameters that are passed to the graphics processor via the 3Dprimitive 932 command are forwarded to the vertex fetch function in thegraphics pipeline. The vertex fetch function uses the 3D primitive 932command data to generate vertex data structures. The vertex datastructures are stored in one or more return buffers. In someembodiments, 3D primitive 932 command is used to perform vertexoperations on 3D primitives via vertex shaders. To process vertexshaders, 3D pipeline 922 dispatches shader execution threads to graphicsprocessor execution units.

In some embodiments, 3D pipeline 922 is triggered via an execute 934command or event. In some embodiments, a register write triggers commandexecution. In some embodiments execution is triggered via a ‘go’ or‘kick’ command in the command sequence. In one embodiment, commandexecution is triggered using a pipeline synchronization command to flushthe command sequence through the graphics pipeline. The 3D pipeline willperform geometry processing for the 3D primitives. Once operations arecomplete, the resulting geometric objects are rasterized and the pixelengine colors the resulting pixels. Additional commands to control pixelshading and pixel back end operations may also be included for thoseoperations.

In some embodiments, the graphics processor command sequence 910 followsthe media pipeline 924 path when performing media operations. Ingeneral, the specific use and manner of programming for the mediapipeline 924 depends on the media or compute operations to be performed.Specific media decode operations may be offloaded to the media pipelineduring media decode. In some embodiments, the media pipeline can also bebypassed, and media decode can be performed in whole or in part usingresources provided by one or more general purpose processing cores. Inone embodiment, the media pipeline also includes elements forgeneral-purpose graphics processor unit (GPGPU) operations, where thegraphics processor is used to perform SIMD vector operations usingcomputational shader programs that are not explicitly related to therendering of graphics primitives.

In some embodiments, media pipeline 924 is configured in a similarmanner as the 3D pipeline 922. A set of commands to configure the mediapipeline state 940 are dispatched or placed into a command queue beforethe media object commands 942. In some embodiments, commands for themedia pipeline state 940 include data to configure the media pipelineelements that will be used to process the media objects. This includesdata to configure the video decode and video encode logic within themedia pipeline, such as encode or decode format. In some embodiments,commands for the media pipeline state 940 also support the use of one ormore pointers to “indirect” state elements that contain a batch of statesettings.

In some embodiments, media object commands 942 supply pointers to mediaobjects for processing by the media pipeline. The media objects includememory buffers containing video data to be processed. In someembodiments, all media pipeline states must be valid before issuing amedia object command 942. Once the pipeline state is configured andmedia object commands 942 are queued, the media pipeline 924 istriggered via an execute command 944 or an equivalent execute event(e.g., register write). Output from media pipeline 924 may then be postprocessed by operations provided by the 3D pipeline 922 or the mediapipeline 924. In some embodiments, GPGPU operations are configured andexecuted in a similar manner as media operations.

Graphics Software Architecture

FIG. 10 illustrates exemplary graphics software architecture for a dataprocessing system 1000 according to some embodiments. In someembodiments, software architecture includes a 3D graphics application1010, an operating system 1020, and at least one processor 1030. In someembodiments, processor 1030 includes a graphics processor 1032 and oneor more general-purpose processor core(s) 1034. The graphics application1010 and operating system 1020 each execute in the system memory 1050 ofthe data processing system.

In some embodiments, 3D graphics application 1010 contains one or moreshader programs including shader instructions 1012. The shader languageinstructions may be in a high-level shader language, such as theHigh-Level Shader Language (HLSL) or the OpenGL Shader Language (GLSL).The application also includes executable instructions 1014 in a machinelanguage suitable for execution by the general-purpose processor core1034. The application also includes graphics objects 1016 defined byvertex data.

In some embodiments, operating system 1020 is a Microsoft® Windows®operating system from the Microsoft Corporation, a proprietary UNIX-likeoperating system, or an open source UNIX-like operating system using avariant of the Linux kernel. The operating system 1020 can support agraphics API 1022 such as the Direct3D API, the OpenGL API, or theVulkan API. When the Direct3D API is in use, the operating system 1020uses a front-end shader compiler 1024 to compile any shader instructions1012 in HLSL into a lower-level shader language. The compilation may bea just-in-time (JIT) compilation or the application can perform shaderpre-compilation. In some embodiments, high-level shaders are compiledinto low-level shaders during the compilation of the 3D graphicsapplication 1010. In some embodiments, the shader instructions 1012 areprovided in an intermediate form, such as a version of the StandardPortable Intermediate Representation (SPIR) used by the Vulkan API.

In some embodiments, user mode graphics driver 1026 contains a back-endshader compiler 1027 to convert the shader instructions 1012 into ahardware specific representation. When the OpenGL API is in use, shaderinstructions 1012 in the GLSL high-level language are passed to a usermode graphics driver 1026 for compilation. In some embodiments, usermode graphics driver 1026 uses operating system kernel mode functions1028 to communicate with a kernel mode graphics driver 1029. In someembodiments, kernel mode graphics driver 1029 communicates with graphicsprocessor 1032 to dispatch commands and instructions.

IP Core Implementations

One or more aspects of at least one embodiment may be implemented byrepresentative code stored on a machine-readable medium which representsand/or defines logic within an integrated circuit such as a processor.For example, the machine-readable medium may include instructions whichrepresent various logic within the processor. When read by a machine,the instructions may cause the machine to fabricate the logic to performthe techniques described herein. Such representations, known as “IPcores,” are reusable units of logic for an integrated circuit that maybe stored on a tangible, machine-readable medium as a hardware modelthat describes the structure of the integrated circuit. The hardwaremodel may be supplied to various customers or manufacturing facilities,which load the hardware model on fabrication machines that manufacturethe integrated circuit. The integrated circuit may be fabricated suchthat the circuit performs operations described in association with anyof the embodiments described herein.

FIG. 11A is a block diagram illustrating an IP core development system1100 that may be used to manufacture an integrated circuit to performoperations according to an embodiment. The IP core development system1100 may be used to generate modular, reusable designs that can beincorporated into a larger design or used to construct an entireintegrated circuit (e.g., an SOC integrated circuit). A design facility1130 can generate a software simulation 1110 of an IP core design in ahigh-level programming language (e.g., C/C++). The software simulation1110 can be used to design, test, and verify the behavior of the IP coreusing a simulation model 1112. The simulation model 1112 may includefunctional, behavioral, and/or timing simulations. A register transferlevel (RTL) design 1115 can then be created or synthesized from thesimulation model 1112. The RTL design 1115 is an abstraction of thebehavior of the integrated circuit that models the flow of digitalsignals between hardware registers, including the associated logicperformed using the modeled digital signals. In addition to an RTLdesign 1115, lower-level designs at the logic level or transistor levelmay also be created, designed, or synthesized. Thus, the particulardetails of the initial design and simulation may vary.

The RTL design 1115 or equivalent may be further synthesized by thedesign facility into a hardware model 1120, which may be in a hardwaredescription language (HDL), or some other representation of physicaldesign data. The HDL may be further simulated or tested to verify the IPcore design. The IP core design can be stored for delivery to a 3^(rd)party fabrication facility 1165 using non-volatile memory 1140 (e.g.,hard disk, flash memory, or any non-volatile storage medium).Alternatively, the IP core design may be transmitted (e.g., via theInternet) over a wired connection 1150 or wireless connection 1160. Thefabrication facility 1165 may then fabricate an integrated circuit thatis based at least in part on the IP core design. The fabricatedintegrated circuit can be configured to perform operations in accordancewith at least one embodiment described herein.

FIG. 11B illustrates a cross-section side view of an integrated circuitpackage assembly 1170, according to some embodiments described herein.The integrated circuit package assembly 1170 illustrates animplementation of one or more processor or accelerator devices asdescribed herein. The package assembly 1170 includes multiple units ofhardware logic 1172, 1174 connected to a substrate 1180. The logic 1172,1174 may be implemented at least partly in configurable logic orfixed-functionality logic hardware and can include one or more portionsof any of the processor core(s), graphics processor(s), or otheraccelerator devices described herein. Each unit of logic 1172, 1174 canbe implemented within a semiconductor die and coupled with the substrate1180 via an interconnect structure 1173. The interconnect structure 1173may be configured to route electrical signals between the logic 1172,1174 and the substrate 1180, and can include interconnects such as, butnot limited to bumps or pillars. In some embodiments, the interconnectstructure 1173 may be configured to route electrical signals such as,for example, input/output (I/O) signals and/or power or ground signalsassociated with the operation of the logic 1172, 1174. In someembodiments, the substrate 1180 is an epoxy-based laminate substrate.The package substrate 1180 may include other suitable types ofsubstrates in other embodiments. The package assembly 1170 can beconnected to other electrical devices via a package interconnect 1183.The package interconnect 1183 may be coupled to a surface of thesubstrate 1180 to route electrical signals to other electrical devices,such as a motherboard, other chipset, or multi-chip module.

In some embodiments, the units of logic 1172, 1174 are electricallycoupled with a bridge 1182 that is configured to route electricalsignals between the logic 1172, 1174. The bridge 1182 may be a denseinterconnect structure that provides a route for electrical signals. Thebridge 1182 may include a bridge substrate composed of glass or asuitable semiconductor material. Electrical routing features can beformed on the bridge substrate to provide a chip-to-chip connectionbetween the logic 1172, 1174.

Although two units of logic 1172, 1174 and a bridge 1182 areillustrated, embodiments described herein may include more or fewerlogic units on one or more dies. The one or more dies may be connectedby zero or more bridges, as the bridge 1182 may be excluded when thelogic is included on a single die. Alternatively, multiple dies or unitsof logic can be connected by one or more bridges. Additionally, multiplelogic units, dies, and bridges can be connected together in otherpossible configurations, including three-dimensional configurations.

Exemplary System on a Chip Integrated Circuit

FIGS. 12-14 illustrated exemplary integrated circuits and associatedgraphics processors that may be fabricated using one or more IP cores,according to various embodiments described herein. In addition to whatis illustrated, other logic and circuits may be included, includingadditional graphics processors/cores, peripheral interface controllers,or general-purpose processor cores.

FIG. 12 is a block diagram illustrating an exemplary system on a chipintegrated circuit 1200 that may be fabricated using one or more IPcores, according to an embodiment. Exemplary integrated circuit 1200includes one or more application processor(s) 1205 (e.g., CPUs), atleast one graphics processor 1210, and may additionally include an imageprocessor 1215 and/or a video processor 1220, any of which may be amodular IP core from the same or multiple different design facilities.Integrated circuit 1200 includes peripheral or bus logic including a USBcontroller 1225, UART controller 1230, an SPI/SDIO controller 1235, andan I²S/I²C controller 1240. Additionally, the integrated circuit caninclude a display device 1245 coupled to one or more of ahigh-definition multimedia interface (HDMI) controller 1250 and a mobileindustry processor interface (MIPI) display interface 1255. Storage maybe provided by a flash memory sub-system 1260 including flash memory anda flash memory controller. Memory interface may be provided via a memorycontroller 1265 for access to SDRAM or SRAM memory devices. Someintegrated circuits additionally include an embedded security engine1270.

FIGS. 13A-13B are block diagrams illustrating exemplary graphicsprocessors for use within an SoC, according to embodiments describedherein. FIG. 13A illustrates an exemplary graphics processor 1310 of asystem on a chip integrated circuit that may be fabricated using one ormore IP cores, according to an embodiment. FIG. 13B illustrates anadditional exemplary graphics processor 1340 of a system on a chipintegrated circuit that may be fabricated using one or more IP cores,according to an embodiment. Graphics processor 1310 of FIG. 13A is anexample of a low power graphics processor core. Graphics processor 1340of FIG. 13B is an example of a higher performance graphics processorcore. Each of the graphics processor 1310 and graphics processor 1340can be variants of the graphics processor 1210 of FIG. 12 .

As shown in FIG. 13A, graphics processor 1310 includes a vertexprocessor 1305 and one or more fragment processor(s) 1315A-1315N (e.g.,1315A, 1315B, 1315C, 1315D, through 1315N-1, and 1315N). Graphicsprocessor 1310 can execute different shader programs via separate logic,such that the vertex processor 1305 is optimized to execute operationsfor vertex shader programs, while the one or more fragment processor(s)1315A-1315N execute fragment (e.g., pixel) shading operations forfragment or pixel shader programs. The vertex processor 1305 performsthe vertex processing stage of the 3D graphics pipeline and generatesprimitives and vertex data. The fragment processor(s) 1315A-1315N usethe primitive and vertex data generated by the vertex processor 1305 toproduce a framebuffer that is displayed on a display device. In oneembodiment, the fragment processor(s) 1315A-1315N are optimized toexecute fragment shader programs as provided for in the OpenGL API,which may be used to perform similar operations as a pixel shaderprogram as provided for in the Direct 3D API.

Graphics processor 1310 additionally includes one or more memorymanagement units (MMUs) 1320A-1320B, cache(s) 1325A-1325B, and circuitinterconnect(s) 1330A-1330B. The one or more MMU(s) 1320A-1320B providefor virtual to physical address mapping for the graphics processor 1310,including for the vertex processor 1305 and/or fragment processor(s)1315A-1315N, which may reference vertex or image/texture data stored inmemory, in addition to vertex or image/texture data stored in the one ormore cache(s) 1325A-1325B. In one embodiment, the one or more MMU(s)1320A-1320B may be synchronized with other MMUs within the system,including one or more MMUs associated with the one or more applicationprocessor(s) 1205, image processor 1215, and/or video processor 1220 ofFIG. 12 , such that each processor 1205-1220 can participate in a sharedor unified virtual memory system. The one or more circuitinterconnect(s) 1330A-1330B enable graphics processor 1310 to interfacewith other IP cores within the SoC, either via an internal bus of theSoC or via a direct connection, according to embodiments.

As shown FIG. 13B, graphics processor 1340 includes the one or moreMMU(s) 1320A-1320B, caches 1325A-1325B, and circuit interconnects1330A-1330B of the graphics processor 1310 of FIG. 13A. Graphicsprocessor 1340 includes one or more shader core(s) 1355A-1355N (e.g.,1455A, 1355B, 1355C, 1355D, 1355E, 1355F, through 1355N-1, and 1355N),which provides for a unified shader core architecture in which a singlecore or type or core can execute all types of programmable shader code,including shader program code to implement vertex shaders, fragmentshaders, and/or compute shaders. The exact number of shader corespresent can vary among embodiments and implementations. Additionally,graphics processor 1340 includes an inter-core task manager 1345, whichacts as a thread dispatcher to dispatch execution threads to one or moreshader cores 1355A-1355N and a tiling unit 1358 to accelerate tilingoperations for tile-based rendering, in which rendering operations for ascene are subdivided in image space, for example to exploit localspatial coherence within a scene or to optimize use of internal caches.

FIGS. 14A-14B illustrate additional exemplary graphics processor logicaccording to embodiments described herein. FIG. 14A illustrates agraphics core 1400 that may be included within the graphics processor1210 of FIG. 12 and may be a unified shader core 1355A-1355N as in FIG.13B. FIG. 14B illustrates a highly-parallel general-purpose graphicsprocessing unit 1430 suitable for deployment on a multi-chip module.

As shown in FIG. 14A, the graphics core 1400 includes a sharedinstruction cache 1402, a texture unit 1418, and a cache/shared memory1420 that are common to the execution resources within the graphics core1400. The graphics core 1400 can include multiple slices 1401A-1401N orpartition for each core, and a graphics processor can include multipleinstances of the graphics core 1400. The slices 1401A-1401N can includesupport logic including a local instruction cache 1404A-1404N, a threadscheduler 1406A-1406N, a thread dispatcher 1408A-1408N, and a set ofregisters 1410A. To perform logic operations, the slices 1401A-1401N caninclude a set of additional function units (AFUs 1412A-1412N),floating-point units (FPU 1414A-1414N), integer arithmetic logic units(ALUs 1416-1416N), address computational units (ACU 1413A-1413N),double-precision floating-point units (DPFPU 1415A-1415N), and matrixprocessing units (MPU 1417A-1417N).

Some of the computational units operate at a specific precision. Forexample, the FPUs 1414A-1414N can perform single-precision (32-bit) andhalf-precision (16-bit) floating-point operations, while the DPFPUs1415A-1415N perform double precision (64-bit) floating-point operations.The ALUs 1416A-1416N can perform variable precision integer operationsat 8-bit, 16-bit, and 32-bit precision, and can be configured for mixedprecision operations. The MPUs 1417A-1417N can also be configured formixed precision matrix operations, including half-precisionfloating-point and 8-bit integer operations. The MPUs 1417-1417N canperform a variety of matrix operations to accelerate machine learningapplication frameworks, including enabling support for acceleratedgeneral matrix to matrix multiplication (GEMM). The AFUs 1412A-1412N canperform additional logic operations not supported by the floating-pointor integer units, including trigonometric operations (e.g., Sine,Cosine, etc.).

As shown in FIG. 14B, a general-purpose processing unit (GPGPU) 1430 canbe configured to enable highly parallel compute operations to beperformed by an array of graphics processing units. Additionally, theGPGPU 1430 can be linked directly to other instances of the GPGPU tocreate a multi-GPU cluster to improve training speed for particularlydeep neural networks. The GPGPU 1430 includes a host interface 1432 toenable a connection with a host processor. In one embodiment the hostinterface 1432 is a PCI Express interface. However, the host interfacecan also be a vendor specific communications interface or communicationsfabric. The GPGPU 1430 receives commands from the host processor anduses a global scheduler 1434 to distribute execution threads associatedwith those commands to a set of compute clusters 1436A-1436H. Thecompute clusters 1436A-1436H share a cache memory 1438. The cache memory1438 can serve as a higher-level cache for cache memories within thecompute clusters 1436A-1436H.

The GPGPU 1430 includes memory 1434A-1434B coupled with the computeclusters 1436A-1436H via a set of memory controllers 1442A-1442B. Invarious embodiments, the memory 1434A-1434B can include various types ofmemory devices including dynamic random-access memory (DRAM) or graphicsrandom access memory, such as synchronous graphics random access memory(SGRAM), including graphics double data rate (GDDR) memory.

In one embodiment, the compute clusters 1436A-1436H each include a setof graphics cores, such as the graphics core 1400 of FIG. 14A, which caninclude multiple types of integer and floating-point logic units thatcan perform computational operations at a range of precisions includingsuited for machine learning computations. For example, and in oneembodiment at least a subset of the floating-point units in each of thecompute clusters 1436A-1436H can be configured to perform 16-bit or32-bit floating-point operations, while a different subset of thefloating-point units can be configured to perform 64-bit floating-pointoperations.

Multiple instances of the GPGPU 1430 can be configured to operate as acompute cluster. The communication mechanism used by the compute clusterfor synchronization and data exchange varies across embodiments. In oneembodiment, the multiple instances of the GPGPU 1430 communicate overthe host interface 1432. In one embodiment, the GPGPU 1430 includes anI/O hub 1439 that couples the GPGPU 1430 with a GPU link 1440 thatenables a direct connection to other instances of the GPGPU. In oneembodiment, the GPU link 1440 is coupled to a dedicated GPU-to-GPUbridge that enables communication and synchronization between multipleinstances of the GPGPU 1430. In one embodiment, the GPU link 1440couples with a high-speed interconnect to transmit and receive data toother GPGPUs or parallel processors. In one embodiment the multipleinstances of the GPGPU 1430 are located in separate data processingsystems and communicate via a network device that is accessible via thehost interface 1432. In one embodiment the GPU link 1440 can beconfigured to enable a connection to a host processor in addition to oras an alternative to the host interface 1432.

While the illustrated configuration of the GPGPU 1430 can be configuredto train neural networks, one embodiment provides alternateconfiguration of the GPGPU 1430 that can be configured for deploymentwithin a high performance or low power inferencing platform. In aninferencing configuration the GPGPU 1430 includes fewer of the computeclusters 1436A-1436H relative to the training configuration.Additionally, the memory technology associated with the memory1434A-1434B may differ between inferencing and training configurations,with higher bandwidth memory technologies devoted to trainingconfigurations. In one embodiment the inferencing configuration of theGPGPU 1430 can support inferencing specific instructions. For example,an inferencing configuration can provide support for one or more 8-bitinteger dot product instructions, which are commonly used duringinferencing operations for deployed neural networks.

FIG. 15 illustrates a data processing system according to embodimentsdescribed herein. The data processing system 1500 of FIG. 15 is aheterogeneous processing system having a processor 1502, unified memory1510, and a GPGPU 1520. The processor 1502 and the GPGPU 1520 can be anyof the processors and GPGPU/parallel processors as described herein. Theunified memory 1510 represents a unified address space that may beaccessed by the processor 1502 and the GPGPU 1520. The unified memoryincludes system memory 1512 as well as GPGPU memory 1518. In someembodiments the GPGPU memory 1518 includes GPGPU local memory 1528within the GPGPU 1520 and can also include some or all of system memory1512. For example, compiled code 1514B stored in system memory 1512 canalso be mapped into GPGPU memory 1518 for access by the GPGPU 1520. Inone embodiment a runtime library 1516 in system memory 1512 canfacilitate the compilation and/or execution of compiled code 1514B. Theprocessor 1502 can execute instructions for a compiler 1515 stored insystem memory 1512. The compiler 1515 can compile source code 1514A intocompiled code 1514B for execution by the processor 1502 and/or GPGPU1520. In one embodiment, the compiler 1515 is, or can include a shadercompiler to compiler shader programs specifically for execution by theGPGPU 1520.

The GPGPU 1520 includes multiple compute blocks 1524A-1524N, whichinclude one or more instances of execution logic described herein. Inone embodiment, each of the compute blocks 1524A-1524N includes multipleexecution units (EUs), where each execution has multiple functionalunits (e.g., ALUs, FPUs, etc.). The EUs within the compute blocks1524A-1524N can be configured for SIMD and/or SIMT operation. The GPGPU1520 also includes a set of registers 1525, cache 1527, and a power andperformance module 1526 that can be used as shared resources for thecompute blocks 1524A-1524N. In one embodiment the registers 1525 includedirectly and indirectly accessible registers, where the indirectlyaccessible registers may be optimized for use in matrix computeoperations. The power and performance module 1526 can be configured toadjust power delivery and clock frequencies for the compute blocks1524A-1524N to power gate idle components within the compute blocks1524A-1524N under heavy workloads. The GPGPU 1520 includes GPGPU localmemory 1528, which are physical memory modules that share a graphicscard or multi-chip module with the GPGPU 1520.

In one embodiment the GPGPU 1520 includes hardware logic including afetch and decode unit 1521 and a scheduler unit 1522. The instructionfetch and decode unit can include logic to fetch and decode instructionsthat can define complex, customizable behavior. The instructions fetchedby the instruction fetch and decode unit 1521 be scheduled via thescheduler unit 1522. The instructions can cause the scheduling of one ormore operations within a set of operations to be performed for eachinstruction. The operations can be executed via one or more of thecompute blocks 1524A-1524N. In one embodiment the scheduler unit 1522 isan ASIC that is configured to perform advanced scheduling operations. Inone embodiment the scheduler unit 1522 is a micro-controller or a lowenergy-per-instruction processing core capable of performinginstructions loaded from a firmware module.

During compilation, the compiler 1515 can analyze source code 1514A andannotate generated instructions that have dependencies on previousinstructions in the instruction stream. The instructions of the compiledcode 1514B will then indicate to the execution logic if execution of agiven instruction is dependent upon the completion of a differentinstruction. The instruction annotations enable the execution logic ofthe GPU to optimize the timing and ordering of instructions withoutrequiring hardware logic to manage data dependencies betweeninstruction. Logic within the scheduler unit 1522 and internal to thehardware logic of the compute blocks 1524A-1524N can then schedule,order, or re-order instruction execution to avoid data hazards.

Instruction Prefetch based on GPU Walker Commands

In one embodiment the instruction fetch and decode unit 1521 can alsoinclude one or more instruction and data pre-fetchers that areconfigurable to pre-fetch data for kernels to be executed by the GPGPU1520 based on GPU walker commands. A GPU walker command provides supportfor spawning threads on the compute blocks 1524A-1524N of the GPGPU1520. Execution of the GPU walker command (or GPGPU walker command) canbe facilitated via graphics drivers using GPU hardware. Workloads (e.g.,shaders) that are submitted to the GPGPU 1520 via the graphics drivercan include a highly parallel section that is executed as a GPU orcompute kernel. The kernel is submitted to the GPU and the GPU walkercommand is submitted to the GPGPU 1520 to replicate the kernel multipletimes. The GPU walker command includes information on the kernel, suchas the kernel address and parameter data for the kernel. In embodimentsdescribed herein, the data provided by the GPU walker command can beused to pre-fetch kernel instructions and parameters early in thegraphics, media, or compute pipeline. A prefetch instruction can be sentto the memory hierarchy after processing the GPU walker command toprefetch instructions and parameter data used by the kernels. Theprefetch kernel parameter data may also be referred to as kernelconstant data in some architectures. The kernel instructions andparameter/constant data is prefetched early in the shader pipeline,before or in parallel with thread dispatch for the kernel. Once thedispatched threads are ready to execute, the instruction andparameter/constant data is already stored in one or more caches of theGPGPU (e.g., cache 1527), internal caches within the compute blocks1524A-1524N, and/or GPGPU local memory 1528. In one embodiment,prefetching data in such a manner can reduce cold start latency by asmuch as 200 cycles.

GPU walker-based prefetching differs from traditional inferredinstruction prefetch in that in traditional instruction prefetch,subsequent instructions can be prefetched into an instruction cachebased on currently executing instructions. With GPU walker-basedprefetching, the specific set of kernel instructions to be executed isprefetched. In one embodiment, the instructions and parameters/constantsare prefetched into a GPU-wide cache (e.g., cache 1527) and whenexecution resources within the compute blocks 1524A-1524N begin toexecute threads of the kernel, local caches within the compute blocks1524A-1524N can be filled from the cache 1527 without requiring a memoryaccess.

While use of a GPU walker command is described, data provided byequivalent commands used in other architectures can also be used as thebasis for early-stage prefetch of kernel data in parallel with threaddispatch for the kernels. For example, a GPU architecture can include aglobal thread dispatcher that dispatches threads to multiple partitionsor compute clusters. In such architectures, when a kernel instruction orkernel constant is referenced by a partition, the constant data may bebroadcast to all partitions and stored in a cache for the partition.Kernel instructions and constants for such architectures can beprefetched to a GPU-wide cache during global thread dispatch, thenprefetched from the GPU-wide cache to a partition cache during localthread dispatch or scheduling within a partition.

FIG. 16 illustrates a general-purpose compute architecture 1600 of agraphics processor, as described herein. The general-purpose computearchitecture 1600 can be implemented within the GPGPU 1520 of FIG. 15 .In one embodiment, the illustrated components of the general-purposecompute architecture 1600 are implemented within the compute blocks1524A-1524N, registers 1525, cache 1527, and/or GPGPU local memory 1528.

The general-purpose compute architecture 1600 includes a commandstreamer (CS 1602), a global thread spawner/dispatcher (TSG 1604), a setof execution units (EUs 1610A-1610N), and a multi-level cache hierarchyincluding at least a level 3 cache (L3 1606) and a last-level cache (LLC1608). In one embodiment, the TSG 1604 receives commands from the CS1602. The TSG 1604 is responsible for unrolling the received commandsand sending individual hardware threads to the available EUs1610A-1610N. Each hardware thread consists of a number of work items.The number of work items determines the SIMD width of the thread. Eachof the EUs 1610A-1610N can concurrently manage a number of such hardwarethreads. In one embodiment, the general-purpose compute architecture1600 additionally includes one or more prefetchers (e.g., prefetcher1605) to speculatively prefetch data into one or more of the caches(e.g., L3 1606, LLC 1608, etc.).

An expanded view of EU 1610N is shown, which is exemplary of each of theEUs 1610A-1610N. Each EU includes hardware support to process multiplehardware threads 1612A-1612N, multiple ALUs 1616A-166B, and a threadarbiter 1614 to arbitrate access to the ALUs. In one embodiment, duringeach clock cycle an EU can execute up to two SIMD4 operations in its ALU1616A-1616B, although in other embodiments the EU is capable ofexecuting a greater number of operations and/or wider operations (e.g.,up to four SIMD4 operations, up to two SIMD8 operations, up to fourSIMD8 operations, etc.). Each hardware thread 1612A-1612N in each EU canhave ALU operations or memory requests ready in each clock, depending onwhether their dependencies on prior operations have been met. The threadarbiter 1614 determines which of the hardware threads 1612A-1612Nexecute their next ready operations. The memory lookups performed by thehardware threads 1612A-1612N are sent to a data cache, such as an L1(not shown) or L3 1606 cache. Memory lookups realize greater throughputwhen there is good temporal or spatial locality in the addresses beinglooked up. Greater throughput is provided because requests that miss thecache are directed to progressively larger and slower memory units, suchas the LLC 1608 and/or random-access memory. In some implementations, athread control unit 1611 is present within each EU to control executionof the threads. The thread control unit 1611 can be configured toperform dependency checks and hazard prevention. For example, the threadcontrol unit 1611 can check and set scoreboard bits for register fileswithin the EU to ensure that instructions are not executed in a mannerthat would cause data corruption due to data hazards.

The CS 1602 can be configured to parse a GPU walker command withincommands provided by the graphics driver. The GPU walker command canthen be provided to other GPU components (e.g., via the TSG 1604) toenable thread dispatch to the EUs 1610A-1610N. In embodiments describedherein, the prefetcher 1605 can be adapted to leverage data provided bythe GPU walker command to perform early pipeline stage prefetching ofkernel instructions and/or parameters that will be used duringexecution. In such embodiment, the CS 1602 can provide GPU walkercommand data 1603, such as a kernel address and a prefetch block size,to the prefetcher 1605. In one embodiment, the prefetch block size canbe calculated by the CS 1602 based on kernel parameter data associatedwith the GPU walker command. In one embodiment the CS 1602 can parse theprefetch block size from the GPU walker command. The prefetcher 1605 cansubmit a walker-based prefetch command 1625 to the memory hierarchy ofthe graphics processor based on the kernel address and prefetch blocksize determined from the GPU walker command. The walker-based prefetchcommand 1625 causes the GPU to load instructions and/or data into one ormore caches including but not limited to the L3 1606 or LLC 1608. In oneembodiment the instructions and/or data is loaded into the one or morecaches, but the instructions and/or data are not provided to the CS1602. In one embodiment, the instructions and/or data is loaded into oneor more heterogenous caches that are shared with a host processor. Forexample, the LLC 1608 may be shared with a host processor. In suchembodiment, kernels loaded or generated by a graphics driver may alreadybe stored in the LLC 1608 and can be prefetched from the LLC 1608 intothe L3 1606.

FIG. 17 illustrates a graphics processing system 1700, according toembodiments described herein. The graphics processing system 1700includes system memory 1712, which can be memory that is shared with ahost processor and that is accessible to a GPGPU 1720 via a systeminterface 1710. The system interface 1710 can be a system interface bus,(e.g., PCIe), a fabric interconnect, or a set of unidirectional links(e.g., NVLink). The system interface 1710 can also enable communicationwith a host processor (e.g., CPU).

In one embodiment the GPGPU 1720 includes a command streamer (CS 1702),a prefetcher 1705, a DMA engine 1707, and multiple graphics, media, andcompute processor cores (first core 1724A, second core 1724B). Each core1724A-1724B can represent a block or tile of graphics, media, and/orgeneral-purpose compute cores, with each core including multipleexecution units, compute units, or compute unit arrays. In oneembodiment each core can be configured as a multiprocessor or streamingmultiprocessor. In one embodiment each core can include multiplegraphics core slices, sub-slices, or dual sub-slices (DSS). Each core1724A-1724B can include a respective local cache 1706A-1706B. The GPGPU1720 also includes a GPU-wide cache (GPU cache 1727). The GPGPU 1720 mayalso include GPGPU local memory 1728. In various embodiments the GPGPUlocal memory 1728 can be a large block of DRAM, such as high-bandwidthmemory or graphics double data rate (GDDR) memory, a smaller block orembedded DRAM (eDRAM). Some low power implementations may exclude someor all of the GPGPU local memory 1728. In one embodiment, a memorycontroller 1708 is includes to facilitate access to the GPGPU localmemory 1728. In one embodiment, each cache (GPU cache 1727, local cache1706A, local cache 1706B) can be associated with a cache controller(e.g., cache controller 1709) to control accesses to the cache and/ormanage coherency operations for the cache.

In one embodiment, the prefetcher 1705 can send a prefetch command basedon a kernel address and prefetch block size determined via a GPU walkercommand processed by the CS 1702. In other embodiments, other types ofthread-dispatch related commands can be used. Any command that providesinformation related to a kernel address and/or kernel parameter orconstant data can be leveraged to enable early-stage prefetching ofkernel data. The prefetch command can be sent by the prefetcher 1705 tothe memory controller 1708 or to system memory 1712 via the systeminterface 1710.

In one embodiment, instead of or in addition to sending a command to thememory controller 1708 or the system memory 1712, the prefetcher 1705can use the DMA engine 1707 to load specific instructions or data intospecific caches or memories. For example, the prefetcher 1705 can usethe DMA engine 1707 to move kernel instructions and/or parameter datafrom system memory 1712 to GPGPU local memory 1728. The memorycontroller 1708 can then load the GPU cache 1727 from the GPGPU localmemory 1728.

In one embodiment, a core cache-miss broadcast prefetch operation isenabled to facilitate pre-emptive prefetching to local caches based alocal cache miss. For example, once the prefetcher 1705 prefetcheskernel instructions and parameters/constants to the GPU cache 1727 andthe threads for the kernels begin executing within the cores1724A-1724B, a first core 1724A may experience an instruction or datacache miss on the local cache 1706A of the core. The first core 1724Acan retrieve the instructions or data from the GPU cache 1727 due to theactions of the GPU walker prefetch. The first core 1724A can alsobroadcast information on the cache miss to the second core 1724B. Thesecond core 1724B can then preemptively prefetch the instructions and/ordata identified by the core cache-miss broadcast from the GPU cache 1727into the local cache 1706B of the core, avoiding the cache missexperienced by the first core 1724A.

In addition to prefetching based on the GPU walker command, the GPGPU1720 can enable support for an explicit kernel prefetch instruction. Thegraphics driver can insert an explicit kernel prefetch instruction intocommand stream of the GPGPU 1720. When the prefetch instruction isprocessed by the CS 1702, the prefetcher 1705 can be configured toprefetch specific instructions and/or data into a specific local cache.For example, instead of the prefetcher 1705 performing a GPU walkerprefetch to the GPU cache 1727 based on the GPU walker command, theprefetcher 1705 can load specific instructions and/or data into aspecific local cache (e.g., local cache 1706A or local cache 1707B). Insuch embodiment, where the local caches 1706A-1706B include separateinstruction and data regions, kernel instructions can be loaded into theinstruction region and kernel parameters or constants can be loaded intothe data region. Similarly, if the local caches 1706A-170B areinstruction caches and the cores 1727A-1724B include a separate datacache, parameter data can be loaded into the separate data caches.

FIG. 18 illustrates a flow diagram of a method 1800 to prefetch kernelinstructions and/or data, according to an embodiment. Method 1800 can beexecuted by a graphics processor as described herein via components suchas, but not limited to a command streamer, thread dispatcher,prefetcher, memory controller, DMA engines/controllers, and/or cachecontrollers. Method 1800 shows an implementation of kernel instructionand data prefetching that can be performed automatically by a graphicsprocessor based on information associated with a GPU walker or anotherthread dispatch instruction.

During execution of method 1800, a graphics processor can receive acommand to dispatch threads to multiple compute units (block 1802). Thecommand can be associated with a kernel to be executed by the computeunits. For example, the command can be a GPU walker command that isparsed by a command streamer and causes the graphics processor hardwareto dispatch threads for the kernel to graphics processor cores, slices,or partitions, or to compute units or execution units within thegraphics processor cores, slices, or partitions. The graphics processor,for example, using a command streamer, can then determine a memoryaddress associated with the kernel based on the command (block 1804). Inone embodiment the memory address is explicitly specified by thecommand. The graphics processor/command streamer can then determine aprefetch block size associated with the kernel based on the command(block 1806). The prefetch block size may be included within the commandor the graphics processor can compute the prefetch size based onspecified kernel parameters or constants. In one embodiment, a defaultprefetch block size can be used. In one embodiment, the prefetch blocksize is provided or determined in terms of a number of cache lines toprefetch. The prefetch block size can be determined, in part based onthe number of instructions within the kernel. The graphics processor canthen prefetch instructions, constants, and/or parameters associated withthe kernel using the kernel memory address and the prefetch block size(block 1808). The prefetching can be performed using a combination ofDMA engine and memory controller operations. The prefetching isperformed in parallel with the dispatch of the threads to execute thekernel. The graphics processor can then load a GPU cache with theinstructions, constants, and/or parameters before start of threadexecution (block 1810). In one embodiment, a GPU-wide cache is loadedand local caches within the graphics processor can be loaded as neededfrom the GPU-wide cache.

FIG. 19 illustrates a flow diagram of a method 1900 to prefetch kernelinstructions and/or data, according to an embodiment. Method 1900 can beexecuted by a graphics processor as described herein using componentssimilar to those of Method 1800 of FIG. 18 . Method 1900 shows animplementation of an explicit prefetch instruction that can be insertedinto a graphics processor command stream (e.g., by a graphics driver) inconjunction with a thread dispatch command, such as a GPU walkercommand. The explicit prefetch instruction can specify a specific kerneladdress and a specific cache, including one or more global or localcaches to which prefetched data to be loaded.

During execution of method 1900, the graphics processor can receive acommand to prefetch instructions, constants, and/or parametersassociated with a kernel (block 1902). The graphics processor can thenprefetch the instructions, constants, and/or parameters associated withthe kernel in parallel with dispatch of threads to execute the kernel(block 1904). The graphics processor can then load one or more specifiedcaches with the instructions, constants, and/or parameters before startof thread execution (block 1906). The specified caches can include aglobal GPU cache or one or more local caches within a graphics core,DSS, partition, etc.

FIG. 20 illustrates a flow diagram of a method 2000 to prefetch kernelinstructions and/or data, according to an embodiment. Method 2000 can beexecuted by a graphics processor as described herein via hardwarecomponents with a graphics processor core, cluster, slice, partition,etc., as described herein. During execution of method 2000, a graphicsprocessor can receive, at a first compute unit, a first threadassociated with a kernel to be executed (block 2002). During executionof the first thread, the first compute unit can attempt to read aninstruction or data from a first cache that is local to the firstcompute unit (block 2004). The first compute unit, in response to acache miss for the read from the first cache, can broadcast a localcache miss event within the graphics processor to identify aninstruction or data associated with the cache miss (block 2006). Asecond compute unit can receive the cache miss event (block 2008). Thesecond compute unit is configured to execute a second thread associatedwith the kernel. The second compute unit can then prefetch theinstruction or data identified by the cache miss event into a secondcache that is local to the second compute unit (block 2010).

FIG. 21 illustrates a flow diagram of a method 2100 to bypass prefetchof kernel instructions and/or data, according to an embodiment. In someembodiments, automatic prefetch of kernel instructions, parameters,and/or constants can result in reduced system performance in scenarioswhere a large number of cache requests are outstanding or in other highcache-stress scenarios. Accordingly, automatic kernel prefetching duringthread dispatch may be bypassed in certain scenarios where a cachestress metric is determined to be over a threshold. For example, in oneembodiment automatic instruction prefetch based on thread dispatchcommands can be bypassed when a number of pending cache requests is overa threshold. The threshold can be configured to a specific defaultnumber of pending cache requests. In some embodiments the threshold canbe configured using a configuration register or a configuration command.In one embodiment the threshold can be dynamically adjusted by thegraphics processor based on available memory bandwidth and/or cacheutilization.

Method 2100 includes for the graphics processor, for example, aprefetcher, to receive a command to dispatch threads to multiple computeunits (block 2102). The command can be associated with a kernel to beexecuted by the compute units. For example, the command can be a kerneldispatch or GPU walker command as described herein. The graphicsprocessor can then determine a number of pending cache requests withinthe GPU (block 2104). When the pending cache requests are over athreshold, the graphics processor can bypass the automatic issue of aprefetch command for the kernel instructions, parameters, and/orconstants (block 2106). If the number of pending cache requests arebelow the threshold, the graphics processor can automatically issue theprefetch command to memory hierarchy (block 2108) and prefetch kernelinstructions and/or data during thread dispatch.

FIG. 22 is a block diagram of a computing device 2200 including agraphics processor 2204, according to an embodiment. The computingdevice 2200 can be a computing device as described herein, such as thedata processing system 100 as in of FIG. 1 . The computing device 2200may also be or be included within a communication device such as aset-top box (e.g., Internet-based cable television set-top boxes, etc.),global positioning system (GPS)-based devices, etc. The computing device2200 may also be or be included within mobile computing devices such ascellular phones, smartphones, personal digital assistants (PDAs), tabletcomputers, laptop computers, e-readers, smart televisions, televisionplatforms, wearable devices (e.g., glasses, watches, bracelets,smartcards, jewelry, clothing items, etc.), media players, etc. Forexample, in one embodiment, the computing device 2200 includes a mobilecomputing device employing an integrated circuit (“IC”), such as systemon a chip (“SoC” or “SOC”), integrating various hardware and/or softwarecomponents of computing device 2200 on a single chip.

The computing device 2200 includes a graphics processor 2204. Thegraphics processor 2204 represents any graphics processor describedherein. The graphics processor includes one or more graphics engine(s),graphics processor cores, and other graphics execution resources asdescribed herein. Such graphics execution resources can be presented inthe forms including but not limited to execution units, shader engines,fragment processors, vertex processors, streaming multiprocessors,graphics processor clusters, or any collection of computing resourcessuitable for the processing of graphics and image resources.

In one embodiment the graphics processor 2204 includes a cache 2214,which can be a single cache or divided into multiple segments of cachememory, including but not limited to any number of L1, L2, L3, or L4caches, render caches, depth caches, sampler caches, and/or shader unitcaches. The graphics processor 2204 also includes multiple GPGPU engines2240 which each include multiple graphics processor compute units orexecution units. In various embodiments, the GPGPU engines 2240 caninclude a GPU walker 2242 and a prefetcher 2244 to perform operationsdescribed herein. Such operations can be performed using a combinationof one or more DMA engines 2246 and/or memory controllers 2248.

As illustrated, in one embodiment, and in addition to the graphicsprocessor 2204, the computing device 2200 may further include any numberand type of hardware components and/or software components, including,but not limited to an application processor 2206, memory 2208, andinput/output (I/O) sources 2210. The application processor 2206 caninteract with a hardware graphics pipeline, as illustrated withreference to FIG. 3 , to share graphics pipeline functionality.Processed data is stored in a buffer in the hardware graphics pipelineand state information is stored in memory 2208. The resulting data canbe transferred to a display controller for output via a display device,such as the display device 323 of FIG. 3 . The display device may be ofvarious types, such as Cathode Ray Tube (CRT), Thin Film Transistor(TFT), Liquid Crystal Display (LCD), Organic Light Emitting Diode (OLED)array, etc., and may be configured to display information to a user viaa graphical user interface.

The application processor 2206 can include one or processors, such asprocessor(s) 102 of FIG. 1 and may be the central processing unit (CPU)that is used at least in part to execute an operating system (OS) 2202for the computing device 2200. The OS 2202 can serve as an interfacebetween hardware and/or physical resources of the computing device 2200and one or more users. The OS 2202 can include graphics driver logic2222, such as a user mode driver (UMD 2223) and kernel mode driver (KMD2224), which can be variants of the user mode graphics driver 1026and/or kernel mode graphics driver 1029 of FIG. 10 . The UMD 2223 caninterface with applications that execute on the computing device andenable those applications to submit to the GPGPU engines 2240 of thegraphics processor 2204.

It is contemplated that in some embodiments the graphics processor 2204may exist as part of the application processor 2206 (such as part of aphysical CPU package) in which case, at least a portion of the memory2208 may be shared by the application processor 2206 and graphicsprocessor 2204, although at least a portion of the memory 2208 may beexclusive to the graphics processor 2204, or the graphics processor 2204may have a separate store of memory. The memory 2208 may comprise apre-allocated region of a buffer (e.g., framebuffer); however, it shouldbe understood by one of ordinary skill in the art that the embodimentsare not so limited, and that any memory accessible to the lower graphicspipeline may be used. The memory 2208 may include various forms ofrandom-access memory (RAM) (e.g., SDRAM, SRAM, etc.) comprising anapplication that makes use of the graphics processor 2204 to render adesktop or 3D graphics scene. A memory controller can be used to accessdata in the memory 2208 and forward the data to the graphics processor2204 for graphics pipeline processing. The memory 2208 may be madeavailable to other components within the computing device 2200. Forexample, any data (e.g., input graphics data) received from various I/Osources 2210 of the computing device 2200 can be temporarily queued intomemory 2208 prior to their being operated upon by one or moreprocessor(s) (e.g., application processor 2206) in the implementation ofa software program or application. Similarly, data that a softwareprogram determines should be sent from the computing device 2200 to anoutside entity through one of the computing system interfaces, or storedinto an internal storage element, is often temporarily queued in memory2208 prior to its being transmitted or stored.

The I/O sources can include devices such as touchscreens, touch panels,touch pads, virtual or regular keyboards, virtual or regular mice,ports, connectors, network devices, or the like. Additionally, the I/Osources 2210 may include one or more I/O devices that are implementedfor transferring data to and/or from the computing device 2200 (e.g., anetworking adapter); or, for a large-scale non-volatile storage withinthe computing device 2200 (e.g., hard disk drive). User input devices,including alphanumeric and other keys, may be used to communicateinformation and command selections to graphics processor 2204. Anothertype of user input device is cursor control, such as a mouse, atrackball, a touchscreen, a touchpad, or cursor direction keys tocommunicate direction information and command selections to GPU and tocontrol cursor movement on the display device. Camera and microphonearrays of the computing device 2200 may be employed to observe gestures,record audio and video and to receive and transmit visual and audiocommands.

I/O sources 2210 configured as network interfaces can provide access toa network, such as a LAN, a wide area network (WAN), a metropolitan areanetwork (MAN), a personal area network (PAN), Bluetooth, a cloudnetwork, a cellular or mobile network (e.g., 3^(rd) Generation (3G),4^(th) Generation (4G), etc.), an intranet, the Internet, etc. Networkinterface(s) may include, for example, a wireless network interfacehaving one or more antenna(e). Network interface(s) may also include,for example, a wired network interface to communicate with remotedevices via network cable, which may be, for example, an Ethernet cable,a coaxial cable, a fiber optic cable, a serial cable, or a parallelcable.

Network interface(s) may provide access to a LAN, for example, byconforming to IEEE 802.11 standards, and/or the wireless networkinterface may provide access to a personal area network, for example, byconforming to Bluetooth standards. Other wireless network interfacesand/or protocols, including previous and subsequent versions of thestandards, may also be supported. In addition to, or instead of,communication via the wireless LAN standards, network interface(s) mayprovide wireless communication using, for example, Time Division,Multiple Access (TDMA) protocols, Global Systems for MobileCommunications (GSM) protocols, Code Division, Multiple Access (CDMA)protocols, and/or any other type of wireless communications protocols.

It is to be appreciated that a lesser or more equipped system than theexample described above may be preferred for certain implementations.Therefore, the configuration of the computing device 2200 may vary fromimplementation to implementation depending upon numerous factors, suchas price constraints, performance requirements, technologicalimprovements, or other circumstances. Examples include (withoutlimitation) a mobile device, a personal digital assistant, a mobilecomputing device, a smartphone, a cellular telephone, a handset, aone-way pager, a two-way pager, a messaging device, a computer, apersonal computer (PC), a desktop computer, a laptop computer, anotebook computer, a handheld computer, a tablet computer, a server, aserver array or server farm, a web server, a network server, an Internetserver, a work station, a mini-computer, a main frame computer, asupercomputer, a network appliance, a web appliance, a distributedcomputing system, multiprocessor systems, processor-based systems,consumer electronics, programmable consumer electronics, television,digital television, set top box, wireless access point, base station,subscriber station, mobile subscriber center, radio network controller,router, hub, gateway, bridge, switch, machine, or combinations thereof.

Embodiments may be implemented as any combination of: one or moremicrochips or integrated circuits interconnected using a parent-board,hardwired logic, software stored by a memory device and executed by amicroprocessor, firmware, an application specific integrated circuit(ASIC), and/or a field programmable gate array (FPGA). The term “logic”may include, by way of example, software or hardware and/or combinationsof software and hardware.

Embodiments may be provided, for example, as a computer program productwhich may include one or more machine-readable media having storedthereon machine-executable instructions that, when executed by one ormore machines such as a computer, network of computers, or otherelectronic devices, may result in the one or more machines carrying outoperations in accordance with embodiments described herein. Amachine-readable medium may include, but is not limited to, floppydiskettes, optical disks, CD-ROMs (Compact Disc-Read Only Memories), andmagneto-optical disks, ROMs, RAMs, EPROMs (Erasable Programmable ReadOnly Memories), EEPROMs (Electrically Erasable Programmable Read OnlyMemories), magnetic or optical cards, flash memory, or other type ofmedia/machine-readable medium suitable for storing machine-executableinstructions.

Moreover, embodiments may be downloaded as a computer program product,wherein the program may be transferred from a remote computer (e.g., aserver) to a requesting computer (e.g., a client) by way of one or moredata signals embodied in and/or modulated by a carrier wave or otherpropagation medium via a communication link (e.g., a modem and/ornetwork connection).

The following clauses and/or examples pertain to specific embodiments orexamples thereof. Specifics in the examples may be used anywhere in oneor more embodiments. The various features of the different embodimentsor examples may be variously combined with some features included andothers excluded to suit a variety of different applications. Examplesmay include subject matter such as a method, means for performing actsof the method, at least one machine-readable medium includinginstructions that, when performed by a machine cause the machine toperform acts of the method, or of an apparatus or system according toembodiments and examples described herein. Various components can be ameans for performing the operations or functions described.

One embodiment provides for a graphics processing device comprising aset of compute units to execute multiple threads of a workload, a cachecoupled with the set of compute units, and a prefetcher to prefetchinstructions associated with the workload. In one embodiment theprefetcher is configured to receive an address of a set of instructionsfor parallel execution by the set of compute units, the address providedvia a command to dispatch the multiple threads of the workload to theset of compute units. The prefetcher can then prefetch the set ofinstructions during execution of the command to dispatch the multiplethreads of the workload. The set of instructions can be stored to thecache before execution of the multiple threads. The set of instructionsare stored to the cache before execution of the multiple threads withoutintroduction of a delay to execution start for the multiple threads andreduces the startup latency for the threads by moving kernelinstructions, parameters, and/or constants to a GPU cache or anothercache that is local to the set of compute units. The prefetcher of thegraphics processing device can prefetch the set of instructionsconcurrently with execution of the command to dispatch the multiplethreads of the workload. In one embodiment the cache coupled with theset of compute units is a global cache for the graphics processingdevice. In one embodiment the cache is local to one or more computeunits in the set of compute units.

In one embodiment the graphics processing device additionally comprisesa command streamer to parse the command to cause the dispatch of themultiple threads. The command can cause the dispatch of the multiplethreads is a graphics processor walker command, the graphics processorwalker command can be executed by walker hardware within the graphicsprocessing device. The command streamer can receive the graphicsprocessor walker command, parse the graphics processor walker command,and provide the address of the set of instructions to the prefetcher.The address of the set of instructions is the address of a kernel to beexecuted by the set of compute units.

In one embodiment the prefetcher can additionally prefetch constant dataassociated with the kernel to be executed by the set of compute units.Prefetching the set of instructions or constant data for the kernel cansubmitting a command to a memory controller of the graphics processingdevice, a system interface (e.g., PCIe) connected with the graphicsprocessing device that enables access to system memory, and/or to a DMAengine of the graphics processing device. In one embodiment theprefetcher can bypass prefetch of the set of instructions based on acache stress metric.

One embodiment provides for a method comprising receiving a command at agraphics processor to dispatch threads to multiple compute units of thegraphics processor, wherein the command is associated with a kernel tobe executed by the compute units, determining a memory addressassociated with the kernel based on the command, determining a prefetchblock size associated with the kernel based on the command, prefetchinginstructions associated with the kernel using the memory address and theprefetch block size associated with the kernel, and loading a graphicsprocessor cache with the instructions before a start of threadexecution. In one embodiment the method can be implemented via hardware,firmware, or microcode within the graphics processor. The instructionscan be prefetched in parallel with dispatching threads to execute thekernel. Constant data associated with the kernel can also be prefetchedin parallel with dispatching threads to execute the kernel.

In one embodiment, the method includes receiving, at a first computeunit of the multiple compute units of the graphics processor, a firstthread associated with the kernel, during execution of the first thread,attempting to read from a first cache that is local to the first computeunit, and in response to a cache miss for the read from the first cache,broadcast an event within the graphics processor to identify aninstruction or data associated with the cache miss. The methodadditionally includes receiving the event at a second compute unit thathas a second thread that is associated with the kernel and prefetchingthe instruction or data identified by the event into a second cache thatis local to the second compute unit.

One embodiment provides for a data processing system comprising agraphics processing device comprising a set of compute units to executemultiple threads of a workload, a cache coupled with the set of computeunits, and a prefetcher to prefetch instructions associated with theworkload. The prefetcher is to receive an address of a set ofinstructions for parallel execution by the set of compute units. Theaddress is provided via a command (e.g., GPU walker command) to causedispatch of the multiple threads of the workload to the set of computeunits and prefetch the set of instructions, the set of instructions tobe stored to the cache before the set of compute units are to executemultiple threads. The data processing system additionally includes amemory coupled with the graphics processing device. The data processingsystem additionally comprises a central processing unit communicativelycoupled with the graphics processing device via a system interface.

One embodiment provides s graphics processor device comprising a set ofcompute units to execute a workload, a cache coupled with the set ofcompute units, and circuitry coupled with the cache and the set ofcompute units, the circuitry configured to receive, at a first computeunit in the set of compute units, a first thread associated with theworkload; during execution of instructions for the first thread, attemptto read from a first cache that is local to the first compute unit; inresponse to a cache miss for the read from the first cache, broadcast anevent within the graphics processor device to identify data associatedwith the cache miss; receive the event at a second compute unit in theset of compute units, wherein the second compute unit has a secondthread associated with the workloqd; and prefetch the data identified bythe event into a second cache that is local to the second compute unitbefore an attempt to read the instruction or data by the second thread.

One embodiment provides a method comprising: receiving, at a firstcompute unit of multiple compute units of a graphics processor, a firstthread associated with a kernel; during execution of instructions forthe first thread, attempting to read from a first cache that is local tothe first compute unit; in response to a cache miss for the read fromthe first cache, broadcasting an event within the graphics processor toidentify data associated with the cache miss; receiving the event at asecond compute unit, wherein the second compute unit has a second threadassociated with the kernel; and prefetching the instruction dataidentified by the event into a second cache that is local to the secondcompute unit.

Those skilled in the art will appreciate from the foregoing descriptionthat the broad techniques of the embodiments can be implemented in avariety of forms. Therefore, while the embodiments have been describedin connection with particular examples thereof, the true scope of theembodiments should not be so limited since other modifications willbecome apparent to the skilled practitioner upon a study of thedrawings, specification, and following claims.

What is claimed is:
 1. A graphics processor device comprising: a set ofcompute units to execute a workload; a cache coupled with the set ofcompute units; and circuitry coupled with the cache and the set ofcompute units, the circuitry configured to: receive, at a first computeunit in the set of compute units, a first thread associated with theworkload; during execution of instructions for the first thread, attemptto read from a first cache that is local to the first compute unit; inresponse to a cache miss for the read from the first cache, broadcast anevent within the graphics processor device to identify data associatedwith the cache miss; receive the event at a second compute unit in theset of compute units, wherein the second compute unit has a secondthread associated with the workload; and prefetch the data identified bythe event into a second cache that is local to the second compute unitbefore an attempt to read the instruction or data by the second thread.2. The graphics processor device as in claim 1, wherein the circuitry isconfigured to prefetch the instructions associated with the workload inparallel with execution of a command to dispatch multiple threads of theworkload.
 3. The graphics processor device as in claim 2, wherein thecircuitry is additionally configured to prefetch constant dataassociated with the workload in parallel with execution of a command todispatch the multiple threads of the workload.
 4. The graphics processordevice as in claim 3, wherein the circuitry is configured to prefetchthe constant data in parallel in parallel with execution of the commandto dispatch the multiple threads of the workload.
 5. The graphicsprocessor device as in claim 4, wherein the command to dispatch threadsto the set of compute units is a graphics processor walker command, thegraphics processor walker command to be executed by walker hardwarewithin the graphics processor device.
 6. The graphics processor deviceas in claim 4, wherein to prefetch the instructions or constant dataassociated with the workload includes to submit a command to a memorycontroller of the graphics processor device.
 7. The graphics processordevice as in claim 4, wherein to prefetch the instructions or constantdata associated the workload includes to submit a command to a systeminterface connected with the graphics processor device to access asystem memory.
 8. The graphics processor device as in claim 4, whereinto prefetch the set of instructions or constant data associated theworkload includes to submit a command to a direct memory access engineof the graphics processor device.
 9. A method comprising: receiving, ata first compute unit of multiple compute units of a graphics processor,a first thread associated with a kernel; during execution ofinstructions for the first thread, attempting to read from a first cachethat is local to the first compute unit; in response to a cache miss forthe read from the first cache, broadcasting an event within the graphicsprocessor to identify data associated with the cache miss; receiving theevent at a second compute unit, wherein the second compute unit has asecond thread associated with the kernel; and prefetching theinstruction data identified by the event into a second cache that islocal to the second compute unit.
 10. The method as in claim 9,additionally comprising prefetching instructions associated with thekernel in parallel with dispatching threads to execute the kernel. 11.The method as in claim 10, additionally comprising prefetching constantdata associated with the kernel in parallel with dispatching threads toexecute the kernel.
 12. The method as in claim 11, wherein dispatchingthreads to execute the kernel includes executing a graphics processorwalker command, the graphics processor walker command to be executed bywalker hardware within the graphics processor.
 13. The method as inclaim 11, wherein prefetching the instructions or constant dataassociated with the kernel includes to submit a command to a memorycontroller of the graphics processor.
 14. The method as in claim 11,wherein prefetching the instructions or constant data for the kernelincludes to submit a command to a system interface connected with thegraphics processor to access a system memory.
 15. The method as in claim11, wherein to prefetching the instructions or constant data for thekernel includes to submit a command to a direct memory access engine ofthe graphics processor.
 16. A data processing system comprising: amemory device; and a graphics processor coupled with the memory device,the graphics processor comprising: a plurality of compute units toexecute a workload; a cache coupled with the plurality of compute units;and circuitry coupled with the cache and the plurality of compute units,the circuitry configured to: receive, at a first compute unit in theplurality of compute units, a first thread associated with the workload;during execution of instructions for the first thread, attempt to readfrom a first cache that is local to the first compute unit; in responseto a cache miss for the read from the first cache, broadcast an eventwithin the graphics processor device to identify data associated withthe cache miss; receive the event at a second compute unit in theplurality of compute units, wherein the second compute unit has a secondthread associated with the workload; and prefetch the data identified bythe event into a second cache that is local to the second compute unitbefore an attempt to read the instruction or data by the second thread.17. The data processing system as in claim 16, wherein the circuitry isconfigured to prefetch the instructions associated with the workload inparallel with execution of a command to dispatch multiple threads of theworkload.
 18. The data processing system as in claim 17, wherein thecircuitry is additionally configured to prefetch constant dataassociated with the workload in parallel with execution of a command todispatch the multiple threads of the workload.
 19. The data processingsystem as in claim 18, wherein the circuitry is configured to prefetchthe constant data in parallel in parallel with execution of the commandto dispatch the multiple threads of the workload.
 20. The dataprocessing system as in claim 19, wherein the command to dispatchthreads to the plurality of compute units is a graphics processor walkercommand, the graphics processor walker command to be executed by walkerhardware within the graphics processor, and wherein to prefetch theinstructions or constant data associated with the workload includes tosubmit a command to a memory controller of the graphics processor,submit a command to a system interface connected with the graphicsprocessor to access a system memory, or submit a command to a directmemory access engine of the graphics processor.